Mom woke up from a nap accusing dad, her caregiver, of cheating on her. How do we change this?

Patient turned on caregiver. The problem is the patient is my mom and her caregiver is my dad. She woke up from a nap one day accusing him of cheating on her and leaving her all alone. She despises him and refuses to see him. It's been a week now. How in the world do we change this? He is her caretaker!!! She can't remember what happened 10 min ago but by golly she remembers that my dad is a cheater and piece of $&@$!