What sort of accommodation is your mother in? If she has her own house, it sounds like it's time she moved to some sort of sheltered accommodation. If she is already in such a place, then it's best to let the managment there deal with her.
Getting her to abandon her own home for a flat in a block full of other old people will be a horrendous struggle, but it has to be done, or you will have no respite over the coming years.
I have to deal with a 93-year old maiden aunt in London, and I know how difficult these problems can be. I live 90 miles away, and I have a number of cousins who actually live a lot nearer. My aunt, however, has managed to fall out with all of them, and won't talk to them any more. There's just me and my brother left speaking to her, and my brother lives in Edinburgh.

We are totally reliant on the manager of the block of flats she lives in, and we need to keep it that way, because otherwise poor Auntie will become completely isolated.