I suspect that your mother's brain is beginning to fail, which is one of the signs that death could be near. This article really helped me to recognize the signs: http://www.caring.com/articles/signs-of-death.
During the two weeks before my mother's death, she accused my brother of selling her house without her knowledge & putting her in a retirement home. She even thought we had fixed up her "room" to look identical to her own home, with pictures on the wall, same furniture, etc. In addition, she began talking to herself, or having conversations with people she imagined seeing.
Do you have in-home hospice care for your mother? If you don't you really need to look into getting it; you & your family need all the help you can get! It's not an easy experience for caretakers, particularly when the patient is confused & is difficult to deal with. Check this out: http://www.agingcare.com/Articles/Medicare-coverage-hospice-care-142914.htm.
I really feel for you, aquart. I know how difficult it is & how alone you & your family must feel.
A big, big to you!