You may be right about someone else driving the vehicles home. The mother's car being parked in the carport could mean that someone was following her car in traffic. She hurried and parked in the carport giving her quicker entry to the house. She may have called her daughter at one of those parties to tell her what happened. Apparently, if this happened, she didn't fear that person enough to call the police. Also, did the mother own any kind of weapon that may have been taken from the house that night. Sometimes people who have a weapon can't get to it quickly enough to defend themselves. Of course this is all theory. I hope someone can think of something to solve this case soon. The culprit, or culprits, could be dead by now.