To be frank, Mom smells. How do I approach this?

Get some outside help - sometimes a care worker can get cooperation about bathing when you are just banging your head against the wall about it.

It appears your mother should not be left alone for an extended period of time. She obviously needs assistance and can't take care of herself properly. I would make appointment with her physician. Who was looking after her while you were away for 4 months? Is she depressed? Poor hygiene can create so many health issues. Are you able to help her with bathing or hire a home health aide? Three times per week might be a good start.

thank you both, Mom has alienated every single caregiver or support team she has encountered, either by calling excessively, changing appt times, or just cancelling altogether when the mood strikes her. She is having a hard time seeing relationships through, all she needs to do is follow through with appts, she wont
Also, she won't just let someone else advise her on a clear way forward, she is sorta just stuck,
but now her physical smell, along with her steady decline is threatening to expose the house of cards she lives in. I need her to have a 2x/wk caregiver capable of all the things she needs done 2x per week, she wont do it, not the money, not anything but her own neurosis now combined w/dementia
She just won't listen
If she does, there is a looming possibility the caregiver will abandon or just sort of peter out in the position.
I'm obviously seeking professional counseling to gain skills I need to cope,
but,
she still needs a bath

It is very difficult but I try to suggest a shower because “someone is coming to visit and we want to smell clean and nice for them”. I have to personally wash my friend down , from head to toe, as he will not properly do so. I tell him how nice his hair will smell with the nice shampoo. Focusing on the positives aspects seems to work, most of the time. I really have to talk him in to it . I mark the day on the calendar. It is a labor of love 💕 and luck,( as how I see it). Good luck!🌺

In order to seek out some answers to what she'd been doing for the past 4 months, check around the house for cleanliness, dirty towels or clothes, dishes in sink, check fridge for presence of food & expired food, trash, mail, unpaid bills, etc. Time for a conversation to let her know that you are concerned about her ability to care for herself & suggest having someone help her. Is she safe to be left alone? Is it time for a doctor to evaluate her cognitive ability while performing a physical? She may have some dementia that is presenting itself to you or has worsened since you left. Sometimes a person will listen to a doctor rather than family when change is needed in their life. Dementia can change their personality which includes paranoia & they may feel you are trying to steal from them. Good luck with you and your mom! 🙏

I can so relate to the not bathing issue. I take care of my next door neighbor whose wife passed away 2 1/2 years ago and both kids are not around (one won't come around and the other is in jail). He had a stroke 3 years ago and has very little movement of the left side of his body. He is also diabetic. And, he's beginning to show some dementia. He has NO short term memory. He has been having urinary incontinence (not sure why although I suspect some laziness) and has been refusing to shower. He makes up all kinds of excuses. I have even come out and told him he stinks and he makes a joke about it. We had a telephone conference (because of COVID) with his PCP and he promised him he would take a shower 3x a week. That lasted less than one week. He even developed (for lack of a better term) "diaper rash" on his backside. Honestly, he can be so stubborn!! One thing we have used in the past and just recently is to tell him we will take him to the casino but he has to shower first. Works every time!!! Now, he's been in the hospital and subsequently a SNF because he developed gangrene and had to have his right great toe removed. Because the artery that was supplying blood to his foot has collapsed, he has to have a below-the-knee amputation done. Dealing with the SNF and the fact that they won't let you in makes it very difficult to get anything done and they want to discharge him!!! I'm working really hard to get him the treatment he needs and hopefully will be able to cross this bridge with him too.