I vote glock 21 of your choices- most reliable. I fired 1300 rounds through mine last weekend. no hiccups. every 1911 clogged or jammed at least 4 times. If you want a light trigger, you can get a 3.5 pound for the glock and it goes in in about 30 seconds. unless you and she have toilet seat size hands, I'd go with a 40 cal glock, maybe a 9mm. data I've seen on the web on hundreds of one shot to the thorax kills demonstrated that 32 hollow point on up to 45 hollow point had a 90 percent kill rate while hard ball ammo of any caliber was about 60 percent. so get a caliber you can afford to shoot, shoot a lot, and pack it with good hollowpoint when carrying.
shoot for the heart or eyes bucket. any other hits, they can still run you down if they are serious. read this story and you'll want to carry a rifle:
http://www.thegunzone.com/11april86.html
in any case, a handgun is a puny weapon and you really can't count on it to get you out of trouble so be cautious. juma