To the OP...there are a few things that must be considered.
First, as it has been stated, the TASER has a limited range. If you get a good hit, with both leads in the target--great. I have been Tased, and have the scars on my back from it. It works--and it works GREAT!
The greatest problem, however, is this: The user might NOT get a good hit. Or, the attacker may be wearing heavy clothing. Either one might generate a REALLY p.o.'ed assailant. If there is one probe in, then a drive stun is possible--but that requires actual contact.
OC works, as well--but you can actually develop a tolerance for it. I have been OC'd about 6 times. Last time, I took a full hit, right in the face and eyes--I wiped it off and beat my attacker with a foam rubber baton for a full minute. OC doesn't work all the time.
You said that she has fired a handgun, and has the potential to be a good shot. If you don't mind me asking--why, then, does she hate guns?
If she actually needs it, Heaven forbid, a controlled application of something like 9mm Golden Saber or Gold Dot beats the h-e-double toothpicks out of TASER probes.
If you can talk her into it, try to get her in contact with a NRA certified instructor, to take her through the Basic Pistol class. Or, get her to a range with a good target grade .22. Put up some paper targets, and let her go through a brick of them. Do NOT mention antipersonnel use. I have found that most women actually have fun once they see holes in the paper.