1. I ditto everyone who recommended having a word of prayer with your manager. Do that immediately.
2. Reading between the lines, this guy is a jerk, and the family doesn't want to deal with him. The family's problem is not your problem.
3. I would also encourage you to take control of this situation. If you are again given this guy's care, walk in the room, greet him firmly, and announce that if he touches you in the slightest, you will call the police. And do it. Do not call security, don't go in the bathroom and count to 10, don't complain to your manager. Just call 911 -- preferably from your cell phone -- and explain where you are -- give the room number -- and that you have been assaulted. Tell them you need the police. Then file a formal complaint. This is your documentation. Honestly, I would go ahead and call the police right now, file a complaint about the past hitting for documentation, but at the very least, don't allow it to happen again without making it unpleasant for both him and the facility.
4. You may count on your managers being annoyed that you've done this. Too bad. You must show them that you will no longer put up with this abuse. As others suggested, take pictures of the bruises, etc., but let there be no more bruises. This guy is a jerk, your managers know that he is a jerk, and you have been given this case -- I suspect -- because no one else will, and you have allowed them to abuse you as an employee.
5. You won't have to go this far, but if he so much as touches you again, announce to your manager that you are resigning from his care. I would let him starve before I would let him hit me again. People like this who are abusive have done it for years and have been allowed to get away with it. You must be one caregiver who will not allow him to be abusive.
6. A facility that allows staff to be abused like this will probably do it to you again. Have you considered looking for a job elsewhere? Good luck. The main thing I would encourage is, again, taking charge of this situation, and making sure it never happens to you again without some unpleasant consequences for this jerk.