My Mom has mild dementia. She is estranged from her husband. They live in separate states. Can she give me POA?

I am the oldest of 2 children.  They are still married but living in different states. My husband and I believe she should live with us as we have the space for her. We would like for her to make the decision to move in with us on her own, before her dementia worsens a she his unable to make the decision. What rights does her husband have?