We believe she has the beginning of vascular dementia. She does not care about anything. Wants to be left alone to lay on the couch and eat whatever she wants. Always looking for sweets and when you get her something, it doesn't last long. Then she wants and looks for more.
And craving sweets is very normal and common with folks with dementia, and there is no happy ending with dementia, so let your mom be.
She clearly has health issues, and one of them may be depression. Please get her to her doctor for a checkup! Your mother's lifestyle is going to spiral downward into REALLY bad health, and then YOU are going to be the one who is miserable, resentful and angry. That's not good for YOUR health.
I wish you luck in learning how to keep your mother healthy and you off the hook as her caregiver.