Re: Is this dementia/depression or Alz
First, I am so sorry for your mother's and your suffering. I am no expert, but have lost father, mother, brother and am old myself.
Your mother is failing in physical and mental ways. She is crying because she is suffering, is my guess. I would try and help soothe her with your presence, your loving attention, holding her hands, and making her as comfortable as possible with the help of a doctor if possible.
Not sure this helps, but it is what I would do.