The window and the door

Ok, so there's a murderer around, and instead of fleeing the house they decide to go to the second floor and enter a room. He obviously follows them, and tries to get into the room.

Then, in a superhuman power, he's able to break the door with his bare hands? WTF is that door made of?

And then they decide to finally leave the house... from the window in the second floor? The girl goes first, she takes her whole body out of the window, to only then notice it's to high to jump? And the mother needs to hold her and push her back inside, while the guy fights the murderer? Why TF the girl left the window and got hunged after all if she wasn't gonna jump???