My only thought about what is going on with your mom is it sounds like demenita of some sort is at least part of the issue.

That said, it was a relief when I learned in my adult years that it is not up to me to fix any of my family members ... only to love them. When they are difficult to deal with, I can love them in prayer while taking care of myself (this may mean keeping some distance and I've finally accepted that this is OK) Sounds like your dad needs prayers, too.