Best case scenario, just don't open the door to begin with...she needs to get over being rude to a stranger on her door step. Even the teen age kid can be a potential threat. An intercom would be a good choice here.
I have seen alot of B&E doors. Most of the time the wood jamb splits apart allowing the door to open. The wood side jamb should be metal or at least have a metal "brass" bracket encasing the wood jamb at the door knob/striker/deadbolt area to reinforce the wood. The door slab itself needs to be of high quality too. If the door jamb is solid, usually the door slab will peel apart on the rolled seams allowing it to collapse on it self and disengaging the locks from the door frame.
The screws being used for any of these security applications should be strong and long enough to penetrate into the frame of the house, not just into the door frame.
A standard storm door lock is not enough to keep anyone out. It needs to be a metal or iron security door. These types of doors will stop em' in their tracks. It will actually drive a would be burglar/intruder to a window or slider door instead, but at least they will not be able to bum rush her if she does open the door...giving her the precious seconds she would need.
Firearms training is a must, it does not stop at the range though...it is a start. Being mentally prepared to deal with a situation is more important than anything else.