Everything is fine with mom and me until her son is in the picture. How do I care for mom in peace?

If in independent living she has to be competent and care for herself, right? Sorry, not going to change her at this point. And u can't control what she does. I wouldn't be around when son is. When she shows no appreciation for what u do, tell her u don't have to do it. That if she prefer ask her son to do it for her. Then walk away for a few days or so. Bet she will be calling u when she finds out son won't and may appreciate u more. There r some parents we have to have borders. You r entitled to ur own life.

If she's incompetent and allows him to steal, it's up to her, but, if she's not competent, I'd explore if he is taking advantage of a vulnerable senior. There's nothing that can change her mind about adoring her son, but, if he's improperly taking her property, that might be something to intervene over.

If you can prove he is stealing from her, go to court and get an Order of Protection.