Definitely don't take matters into your own hands at this point, your daughter needs you close. I'm going to echo what others have said as far as calling the police. Get out in front of this, they need to establish hand prints/bruising so if this guy tries this with anyone else in the future (Hopefully not your daughter, or anyone really) that he's got a known history of violence and can be punished accordingly. He should probably be spending some time behind bars as it is. Lessons don't get learned with slaps on the wrist, there's a good chance he'll just escalate the behavior to get what he wants next time. Restraining order should be a priority I would think.
In the meantime, until he either cools off or is put away, consider moving her in with you for her own protection. If she's unwilling to leave her current residence, I would suggest upgrading security measures and maybe notify some close neighbors so they can keep an eye out if he's prowling the area. Let them know what kind of car he drives, description, etc. Keep lights on around the property at night. I would advise that she not be alone for the immediate future till the situation de-escalates.
I'm sorry for your daughter and your family, nobody should have go go through that kind of crap. It can be scary what crazy ex's are capable of. I've not been on the physical end of it, but I've been stalked and gaslit myself. I'm glad your daughter wasn't seriously hurt, some aren't so lucky. Not only has he been physically abusive, but certainly mentally and emotionally. She's going to need a lot of healing to overcome the crap he's put her through. I wish you guys the best.