A couple of suggestions
This isn't answering your question, and I apologize in advance if that's annoying to you, but since a couple of other people have added additional 2 cents, I hope it's all right if I add mine.
First, I hope someone qualified is going to give this girl some TRAINING. Safety rules, safe gun handling skills, over and over and over. How horrible would it be if she gets injured not by the stalker but from her own unfamiliarity with firearms?? Once she can recite the basic rules and knows them physically (muzzle control, finger off trigger, etc.), more training on how to use the weapon defensively.
I also wonder if a revolver -- say, a .357/.38sp -- wouldn't be more newbie-friendly. Also harder to take away from her in a struggle than a long gun. I'd go with the .357/.38 instead of straight .38, so that, if she gets more comfortable with it, she can use .357, now or in the future. She can also train more at the range with a revolver than with a shotgun because of less physical fatigue (from racking [assuming it's a pump] and from recoil).
Lastly, I agree with the cell phone with her at all times suggestion. I would suggest also that, in this "home alone" situation (which should be minimized, obviously) she have a land line as her first attempt to get 911 on the phone. It can be a cordless phone so she can be mobile (look out windows, lock doors, stay away from windows, etc.). The good thing about that is that 911 can sometimes trace the call and find her even if she is interrupted and drops the phone. My fiancee once made an emergency call, the line got cut before she gave the address, but somehow the law showed up, guns drawn, expecting a possible hostage situation. Everything was fine by then, but it was interesting. Also, on this topic, have her PRACTICE what she's going to say when she dials 911. One of the first things she says should be the address where she is, in case she's cut short by BG coming into house, etc.
When I was 14 I had to dial 911 because of domestic violence in my house, and I, rattled as hell, dialled 411 (information), because that's all I had ever dialled before. She should practice everything she should do, physically, not just mentally/verbally. She will feel more secure from knowing what she's going to do under what circumstances.
Lastly, I hope she can get some good counseling after this. She may need a lot of it (I mean years) and there's no shame in that at all. This perp has no right to turn her into a terrified, damaged human being, and a good therapist can help her turn this into a growth experience (pardon the touchy-feely phrase, but it's the best expression I can come up with) and not a wound that won't heal.
Again, please pardon the unsolicited advice. I really hope everything turns out as well as it can at this point. I hope her mom is okay, too. Sounds like a vulnerable situation.
