Hello Lozza and welcome to the forum.
What a time your father has been having.
General Hospitals are not friendly places for people who are confused, delusional, hallucinating. You say your father was getting confused before he had the fall which resulted in his hospital stay. This could have been caused by his medication, or an infection, or dehydration or just a progression of his condition. Equally his present confusion and aggression could well be caused by the dehydration you say he has suffered in hospital.
It sounds as if your mum has maybe reached the end of her tether. Perhaps things have been worse than she has let on to you. It definitely seems as if they need some help and support. Will they let you talk to their GP? Do they have a Parkinsons' nurse? If so she would be the person to approach. Or try the helpline (phone number at the top of the page). Believe me this has all happened before to other people. You are not alone!
Do keep posting and let us know how things go.