What do you do to help a parent who has become hateful to all her family?

Your father needs to tell her doctor what is going on, so he can evaluate what the cause is. Could be anything from dementia, depression, to urinary track infection. It will probably make her mad to have to go to the doctor, but it sounds like she is anyway and maybe the doc can prescribe something that will help. Best Wishes!

Has she been evaluated for possibly having bi-polar disorder?
Has she always had the mood swings?
Has she been evaluated for dementia?
What meds is she currently on?

She has some health problems but is followed by her doctor. My Father POA for her and I assist him. She is not a danger, we do not know how to handle the mood swing, from happy to sad to angry in a blink of an eye

What are her health problems?

Has her doctor seen her recently?

Who has durable and medical POA for her?

Is she a danger to herself and/or others?