Two possibilities come to mind: mental disorder of some kind and Alzheimer's. Somehow you have to get her to someone who can diagnose her, and that doesn't have to in a mental hospital if she's not a danger to herself or others. It can be seeing a psychiatrist who specializes in older people or even her regular doc if she has one she trusts who can guide her to the right people and comfort her that it's the right thing to do. Does she have a doctor who speaks Spanish (I'm assuming she does because you used the term abuela)? But without a diagnosis that you trust you can't decide on a course of action.