Narcissistic mom who is money hungry. Any advice?

I have read where some caregivers (money manager in your case) give their LO an allowance for the week. It’s not just a choice for NHs.

Create a system. Add up her expenses and be sure to charge her for her portion of utilities and a savings. Then whatever is left divide by 5 and that’s what she gets each week. If DH is going to pay for fast food add her portion of that to the expenses.
So hypothetically lets say she has $100 after insurance and meds and Her portion of living expenses. So she gets $20 a week. Save the last $20 for a little savings for when she needs something besides pocket money.
THEN if DH is blowing HIS pocket money that’s another conversation.
Oh and get a plastic cover for the thermostat, a thermostat you can control from your cell phone or maybe just move the clock.
Its tough being mom to mom.

Just a note.
There are types of dementia that develop very slowly. I saw my aunt adjust her thermostat and deny it for years before diagnosis. Your mom probably is actually cold. Just make sure she has on some nice warm socks and cuddle dud underwear layered with her regular clothes can keep her comfy.
Give her a cup of tea or other warm beverage. Hopefully she’s not drinking iced drinks or ice cream and then turning up the heat.

I do have a POA and her money is direct deposit into an account in her and my name so I do pay the bills from the account. My biggest problem is the nagging/whinning of that she has no money. And it drives me crazy she always wants to go out to eat at a fast food place. So, I let her then with out me knowing she will take my husband with out me knowing and paying for it. I had let him know he has to tell me. We put a small space heater in her room and she has it 80 in there which we don't mind because she is not heating the house that high. We just figured out what she is doing there is a big clock over the thermostat and she will go very close and change letting us think that she is looking see what time it is. She has glaucoma in one eye so the dr said she really can't see that good. I guess I didn't realize how sneaky she could be. And the drs.' and her sw insist that she does not have AL or D. She is just old.

I agree with Tothill except that I dont think SS will take a POA.
Go to the drug store and tell them that you need to move mom’s refill date until after her check comes in. If you need to, pay for a few days pills with the remainder coming in after her check does. If she wants the pills she can pay for them then.
Put the thermostat where you find it comfortable and remind her she has sweaters. When she starts paying the bills she can have a larger say.

Do you have POA? If not, please look into getting it. Tell Mum that she cannot live with you if you do not have it, according to the lawyer. Do you have a contract with her about who pays what? If not, get that written up too.

Once you have POA arrange for her SS to be direct deposited into a new account. Pay Mum's share of the bills, food etc, then let her have what is left over.

Who cares what she says when you ask her to contribute to the household? Every adult should be making a contribution to the running of a house.