Mom in NH, says she doesn't know if she's staying or not. What would you say or do?

My mom, 90, had a stroke in July, broke her hip in Memory Care in September. She has vascular dementia, and perhaps Alzheimer's, along with CHF. She's currently in a NH, where she did rehab for her hip; she's now there as a private pay patient; mostly seems contented. I asked the other day if I should put up her college diploma, wedding pictures and other significant mementos in her room. She said "well, I may not be staying here for long". I decided to let this go in the moment (my brother who is POA is out of town, she was upset about some other things and I didn't want to query and get into a row without an exit strategy. But I'm curious how others would deal with this sort of question/statement. Should we explicitly tell her that this is where she's staying long term? Shine her on with "till it stops snowing"? How do we determine if she might be better off in memory care, as opposed to NH?