How do you deal with parent with Alzheimer's that is physically aggressive?

There are meds that can be prescribed. If he does hit you or Mom, call the Police. Tell them you can not have him in the home because he has violent tendancies. He needs to be taken to the ER and maybe transported to a Psychic Hospital. This may be the time to consider a facility for him.

Has he been seen by a geriatric psychiatrist?

No one should live in a home with an unpredictably aggressive person. If you have no other recourse, call 911 and have him transported to the ER.

But a far better path is to talk to his doctor about how to get him admitted to a specialized psychiatric unit for seniors.

This is when we decided to put my Dad in MC. He was wearing us all out and no one was getting any sleep. He did very well there,, we started off with a month respite stay and he was there until he passed ( in a month,, he had some co morbidities)