How do I protect Moms finances without paying a ton to either a lawyer or brother?

There is no probate involved. Everything was held in Joint Tenanacy with Rights of Survivorship. Nothing is in probate.

My Mom is the sole inheritor. There is no assets out side of what was held jointly

As for..hire an attorney. I cannot do that. I cannot justify $350 per hour. That is exactly my brother's threat. "Pay me or pay and attorney...either way..you lose".

My brother has nothing. Winning a judgement against him for money is worthless....he has nothing outside of his Social Security which is untouchable.

That is what makes his blackmail so effective. He can cost Mom thousands and he is collection proof himself.

I assume you are doing proper probate with an attorney and filing proper papers with probate court. He has to file a claim there, as part of probating Dad's estate. He won't, he can't afford an attorney.
Get an Order of Protection if he is threatening harm to you or mom.
I know you talked about putting your name on mom's accounts. Be aware that if you do that, as executor or POA, you will be is serious legal trouble.

Does he come to your house?
Does he come to your mother's house?
Where or how exactly is he threatening you?

I think your brother is trying to frighten you into handing over money. It's a tactic. In my opinion, your brother will be hard pressed to find an attorney willing to take his "case". Nonetheless, I think a restraining order is your best course of action unless he finds some dope to file a claim.

That said, I agree with Cwillie. Even if you cannot record him because you live in a state requiring two-party consent, you can put him on speaker while having someone in the room with you to witness the conversation. It would not be a bad idea to video record you (speaking with your brother) and your witness (not saying a word and just listening) while your brother is on speaker.

Why do you feel that you need to answer your brother's threatening communications in the first place?

Bro is a pig. Check the law in your state to see if you can legally record him on the phone. If yes, start recording phone conversations and printing out texts and emails. Get him riled up and talkative, the more he says the better. Then take everything you have to the police and an attorney and ask how best to proceed. My hope is that any suit he brings forward would be dismissed based on his admission of malicious prosecution. If not I would rather pay lawyers than allow him one red cent, then I would sue him for court costs when he loses.

Contact the police ASAP and also find an attorney ASAP who can set your brother straight on this attempted blackmail. He might be gambling that he can threaten or scare you into forking over $40K.

Research law firms to find an attorney who's handled probate litigation; you need to make sure to select someone who knows how to handle dissatisfied siblings who were excluded as heirs.

Was there any provision in your father's Will addressing someone who challenged the terms of the Will?

And if he does sue, make sure you have a good attorney who includes in the "prayer" (part of the answer to a complaint) your request that the court compensate you for emotional distress and costs, including but not limited to attorney fees. Your brother needs to be aware that he can be assessed with those fees.

He's wrong if he thinks he can "just drain" the account - he can also be assessed with filing a nuisance complaint penalties and end up bankrupting himself.

If he lives anywhere near you, you might also think about asking the police how to get a restraining order. Anyone this malicious might go beyond suing.

And BTW, I don't see any cause of action against your mother; she's the heir; that was your father's choice.