Getting a guardian. Any advice?

OK, I have problems with mother, who is 77, has dementia, lives alone, doesn't do anything, doesn't get along with anyone in her family. She wants no extra help, except for someone to get cigarettes and her xanax -- she literally just called, after not talking to me for a month (when she told me never to talk to her again or she'd call the cops) and asked me to get xanax and painkillers for her.
I've had ups and downs for years -- usually things end for spells because she makes wild accusations or screams at me or threatens to call the cops on my husband and me because she thinks we stole something like a Garfield figurine.
She's been in the hospital a few times the last few years, has had psych evaluations and talked to nurses and social workers there. Many seem to think she's at the point where she will soon (possibly very soon) need a guardian.
Now, I don't want to do it. There's too much anger on both our parts, and she constantly makes accusations, insults me, and then if I don't jump to do something right away she threatens suicide or calls me names, etc.
But I've called the courts and her doctor. The court says to get a guardian assigned, I need a doctor's note. Her doctor, however, says she is fine and doesn't need a guardian. The court says they won't do an evaluation because I said I hadn't seen her in a month. So what do I do -- wait for her next episode and call the court right away about getting a psych evaluation?
I'm so tired of this all. I've literally been going through these issues for more than a decade and I'm tired.
What can be done at this point?