What to do with mom who sleeps all day and all night. She has dementia and a feeding tube and she cannot do any thing for herself?

If she is truly in the final stages, as the feeding tube would imply, I'd talk with the doctor about hospice. Feeding tubes have their place, but rarely for someone in late stage dementia. If she's on the feeding tube for reasons other than late stage dementia, it's possible she should be re-evaluated. Sleeping in the end stage before death is normal but a medical professional should determine if that is the case with your mom.
Take care of yourself,
Carol

Is she is a skilled nursing facility?

Have medical professionals suggested she is in the final stage of her dementia? Is she on hospice?