2 questions

Thank you. Yea I mean the Mandrackas (Idk if I spelled their last name right or wrong lol) really didn't help themselves living so far out...Feel like the stranger could easily of been hiding at a distance and watching for a while. If he were to see any car head towards their house he could see it as a possible opportunity. He also could of just been hiding out in the guest house for the longest time and when ever the son came home he could of attacked him just like how he did in the beginning of the movie with the house by the carnival.

I just re watched the scene when she runs to the guest house....All she does is pad locks the door. No bottom handle lock, no chain lock. Just a simple pad lock. So the stranger probably just picked the lock, remember when Jill walks back in the alarm was going off. So he probably set it off, and it is possible that he answered the phone for the alarm company and maybe knew the right thing to say.... Or it is a plot hole that the alarm company did not call.