The management needs to deal with this NOW. Part of their job is to make sure that any thing broken is fixed, not to mention if it deals with the tenets safety. She should check her lease and see if it mentions how long the management has to fix something. My personal apt has a 2 day fix, and if they dont then they take a certain amount off of our rent, every day that it doesnt get fixed. Also, she would have to get permission to fix the door themselves, I believe.
Also, it seems to me, that with all the incidents going on that she should have an opt out clause in the rest of her lease because this isnt a safe environment anymore. She should also look into this as well.
I dont blame her one bit for being concerned about herself, and her child. It's more than a one time incident.
Has she called the police?? They can start doing drive by's the complex and have them watch the place, hopefully that if it happens again, maybe they can catch them. And at the very least, have documented statements made out with the police department so they know its a reoccurring thing.
Tell her not to be afraid to make some noise to get the door fixed, and something done about safety in their complex.