If my 96 yr. old mom wants to sleep more, is it ok?

Why not? Is she late for work every day or something? (Yes, I'm being sarcastic.)

She's 96 and winding down, for heaven's sake. Let her be.

As people age and even as they draw nearer to dying they will sleep much more, so I wouldn't be concerned. Your mom is 96 and I'm sure her body is beyond tired at this point. It may be time to bring hospice on board or at least have her evaluated for it.
My late husband(who was under hospice care in our home)slept anywhere from 16-20 hours a day for the last year of his life.

Yes, I would. It is the normal progression, even for elders WITHOUT any dementia. Let her sleep.

I would. I do believe its better to try to keep regular meal, medication and bathroom schedules but there's no reason she can't lie down and nap the rest of the day if that's what she feels like doing.