Is the mother actually suing? I brought it up as a hypothetical. Like some have pointed out, the mother could just claim emotional distress or PTSD from the incident. You get the right/wrong judge depending on the way you look at it, and who knows what will happen.
I worked with a guy who rear-ended a SUV or minivan. The police even estimated in their report that he was going 3-5 mph in his rabbit when he hit them. The guy and his wife sued, claiming the accident left him impotent and he settled for just under 4 million dollars.