First, press criminal charges. Then, file a civil suit.
Thankfully, the mom comes off as reasonable here. You've gotta feel for her. I wonder where dad is.
Update: OK, no civil suit against mom. She doesn't look like she has much to give, and she certainly didn't condone her son's behavior. I have a hard time imagining being pummeled like that poor (substitute) bus driver was, though, and not seeking some civil damages.
But I'd still definitely press criminal charges.