ending
I don't know what ending were you watching but from the one i watched i couldn't possibly say that everyone died at the end. Mother, son, daughter and then daughter's son were still alive just before the end.
Then there are three wierd scenes where the daughter and son escapes and boyfriend drives them off to a tunnel, and a scene when the boyfriend enters the house - this onen i don't understand. and then the movie stops.
the only person i think that dies is father.