He had major health issues and she has dementia. He passed away in March. Now she cries and says she does not want to live alone. Should we leave her in assisted living or try to move her into one of our (her children) homes. I feel her dementia is too advanced to live alone.
I think it is much too early to make any long term decisions about a change in the living situation. She had a major move in Januray and a life-changing death to deal with in March. April is too soon to make more changes! As a recent widow I can tell you that the rush of conflicting and uncomfortable emotions is overwhelming, even if you are healthy, independent, and have good support. There is a reason that many mental health "experts" advise against major decisions (moving, selling a house, remarrying, etc.) in the first year of bereavement.
Even if your Mom did not have dementia and were still living in her home, she might be crying now and saying she doesn't want to live alone. That's not the dementia, that is grief.
Be patient and supportive as the mourning plays itself out. Six months from now is soon enough to start wondering if changes should be made.