You need to discuss this unhappy situation with your mother's nurses and doctors, and if she will talk about it and can with your mother.
There comes a time for many of us, perhaps all of us, when life no longer holds any allure. If your mother is at this crossroads, you and the medical team caring for her ought to accept that at 92, she has lived a long life.
I know it is hard to lose your mother, but I found it easier to lose my 89 year old father, who like your mother may have done, had decided that enough was enough, than to lose my 67 year old husband or my 60 year old sister, but realised that life held only suffering for them if they battled on. They all died peacefully and with no pain, and honestly I do not think any of us can wish for more, when our time comes.