Yeah he's probably a little freaked out, so even if you grab him he may scratch and bite to get away. It's not that unusual with housecats; they get so overwhelmed at being outside that they kind of lose it.
Can you rent a live trap? Otherwise just keep trying to lure him back to your parents' house and try to get him in the door.
Can you rent a live trap? Otherwise just keep trying to lure him back to your parents' house and try to get him in the door.