I agee that the legal ordeal is likely far from over for this woman. It's sad really. She absolutely did the right thing.
Ordinarily I'm not into folks going out of their way to get involved in a situation, but there are times (like this one) that call for it. Since neither the robbery victim/son or his girlfriend were able to protect themselves against this CRIMINAL, the fact that his mother was able to come to his aid and stop the attack makes her a hero.
We've all heard (or ever said) it before: When seconds count, the police are only minutes away.
Now, I sincerely hope that if they can legally do so, the son and his girlfriend will arm and train themselves.