It's entirely possible that the scenario ccane just put out there is the way it happened - especially if the mother became enraged as she was driving from work (wherever that is) to home, feeling fed up with her daughter's "wandering off" and having to leave work early to come find her - especially if she had had to do so on previous occasions.
And who knows what else was going on in her private life or at work? Maybe she got chewed out by her boss, maybe she was having relationship issues (not to mention what looks like is shaping up to be nasty divorce/child custody issues), or financial issues (I'm not saying these are excuses, just trying to paint a scenario). Maybe her daughter wandering off again was the final straw and she "snapped". We know so very little about the family dynamics. Are there anger issues? If she did do it, then yes, there would have to be anger issues.