My mom thinks my dead brother put a curse on her. Any advice?

no

I agree with ZippyZee - since your mother irrationally believes in the supernatural, then the supernatural will have to be the "cure."

Suggestions:

Do a ritual to 'remove' the curse.
Maybe even do a series of ritual.
Plant a 'sign' that means your brother has forgiven her and moved on.
Send her note from brother.
Do a cleansing of herself to remove negative energy.
Buy her a 'protection charm' to wear.
Take her to see a 'psychic' friend.

Good luck to you. Let us know if anything works.

I'm assuming that your brother was a legal adult when he died. She's not responsible for his debts. Also, he's been gone 20 years like you say. No one is trying to collect any debts anymore.
More likely your mother is working herself up with this nonsense because she wants attention and thinks you aren't paying her enough.
Let her do what she wants with her money, but make yourself plain to her that if she wants to waste her money on nonsense that you will not help her out financially.
She is also using this "curse" nonsense as an excuse to be furious with you and to lash out at you. I don't think so. Do not play into her delusion nonsense, and whatever you do, do not tolerate her abusive behavior.

Get some garlic to tie around her neck on a cord? Your mother obviously has some psychiatric issues or dementia issues that should be addressed by the appropriate medical experts. If I recall, it's been a series of issues with her in the past, with this 'curse' being the latest in a long line of problems, right?

You'd do well to get her evaluated. If she refuses to be evaluated, you'd do well to minimize your contact with her & keep your visits to a minimum. There are some people you just can't interact with. My mother was one of those also; impossible to get through to, so I kept my contact down to a minimum with her. Her old Italian upbringing lent itself to histrionics and she insisted the 'evil eye' was real and that others 'had it in for her' and all sorts of other nonsense. She wore a horn around her neck to ward off the evil eye too. Maybe your mom would do well with one of those?

https://www.ebay.com/itm/255089900057?hash=item3b648afa19:g:Ia8AAOSwy4NhFX7g&amdata=enc%3AAQAHAAAA4M28tR4SbqlzkqGfaKfeY1ZEN05e8u%2FXzkgt8biXwJ2aMvtt%2FycQozDpNIWvVSWpRtvSOJxsaHNhUXHDfbdySCov5jIW8ONfiBa%2BJV8nvWdrkVywSgZlxOVqLbNqe%2BqP0LHULLMGPtHf2RBhzVQ%2FqpFBrmeH0LWWzc0lIF9bIuBUttULLsAJz4oCSA9Ob5X1Bmodm6GeVWSTB6Y6R8lVSHgun%2B5sjXwcUsdssj6rUkn48UJNH93dy2T9mXA1lBNsqAL8CMoDbBPRZh8nTlzHwZ%2B06y7KaGjdnDLaDmfwVH0w%7Ctkp%3ABk9SR_zT0bz0YA

Trying to treat an unreasonable person with logic & reason doesn't normally work. Just ask me, I know. ((((Eyeroll))) Which is why I suggest the horn necklace. If she thinks the horn will ward off evil and/or a curse, then it might just DO that, at least in her mind.

Good luck with a difficult situation.

20 YEARS?

And the 'investment' is worth $1k? I would take it and donate it if if bothered me.

Actually I am really sorry your mom paid off all uncles' bills. That was nice of her, and she certainly didn't need to do it---my brother died highly in debt and trust me, the creditors came after everyone they could.

My FIL left some worthless property in NM for us. I now pay taxes on it every year that are more than the value of the property. I want DH to check this out and dump the property. He refuses, so I guess OUR kids will be dealing with this ridiculousness.

I don't think dad is cursing up from beyond the grave, I think he's embarrassed. Every 6 months i write that stupid check and I swear I feel his embarrassment.

Your Mom was not responsible for her sons debts. If she used what money he had to pay some of his debts, thats all she needed to do. She was not obligated to use her money to pay his debts even by law. Debts have an expiration date. They have been written off the books ages ago. No debt is hanging out there for 20 yrs after someone dies. Why would brother even think she should have paid them? This is irrational.

If he had children, give them the info on the retirement fund. If no children, you can talk to them. They will probably turn it over to u. Its probably been set up as an annuity and its costing them money. Maybe Mom is beneficiary. All she probably needs to do is sign something and she will get the check.

Tell Mom brother has left her something good. Except it. If she doesn't want it, give it to her Church in his name. Was there a charity that he liked? Donate the money to that. Tell her if she does not except it, the State will end up with it. Its not a curse, its a blessing for whomever she donates it to. The holidays are coming. Toys for Tots is a good charity to donate to. Salvation Army, it will help pay for holiday dinners.

Where I used to live, you could hire a “root doctor” to remove or put on a curse. Low country of South Carolina. Did she ever
live there? If so, maybe that’s the origin of her belief.

Airwick's post has been reported, but others...please do so as well to get rid of this low class, vulgar post.

If these funds are not claimed they will go to the state. Mom is not in charge of settling the debt. However if this is brothers money and a debt is owed then this money will need to go to that debt. Also, if mom believes that there is a curse, it was suggested to do a ritual to undo the curse - that is great idea!
Prayers for you and yours

Family is not responsible for other family member's debts. I don't know how you convince your mom otherwise, but the money in brother's retirement account does legitimately pass to immediate family and you don't need to concern yourselves with any of his debt.

Conduct an elaborate ritual to break the "curse"?

The company should turn over the money to the state to handle. Every state has an office which handles "lost" funds from businesses that don't know what to do with money they owe someone. This is what happens to unreturned utility deposits, dormant bank accounts, unclaimed final paychecks, stocks and much more. Google Unclaimed Property for your state to see how easy this is to find money.
If mom doesn't want the money, for whatever reason, maybe you can find out what else can be done to claim it. Everyone should check on themselves and loved ones. You should be able to access information online to see if there is any unclaimed property and how to get it. I personally found money owed to me. I happened to go in person to claim it and the folks in front of me got about 25k from Grandma's stock they hadn't even known about before. Also you can find out about auctions where the state may auction off some items that might have been in safe deposit boxes, like jewelry or stamp collections. MANY people have found money they didn't know about.

Definitely a physical and cognitive assessment, ideally by specialist(s) in GERIATRIC CARE.

I'm not sure how to combat an imaginary curse. Your Mom is being irrational. If she has always been irrational, then I don't have any advice. But if this is new/different/unusual behavior for her and she is 60+ years old, then I would start by getting her to Urgent Care or the ER to check for a UTI. After she has been cleared of a physical medical issue, then I woud work on getting her a cognitive exam. Whatever the outcome is from that, then you will know what direction to take it with her.

Are you her PoA? Is anyone? This is the person who now needs to step in to figure out what is going on with her.