I'm assuming that you don't have anything chambered in 22LR at this point (
edit: just noticed you have a P22 - has she tried that out?). If not, I'd start their and not 22 Magnum. 22 Magnum recoil and noise aren't bad out of a heavier revolver with a longer barrel, but out of a short (2" I'm assuming) barrel they produce an ear piercing, sharp crack that could be bothersome for a newbie. Recoil probably won't be too bad, but it would certainly be more noticeable than a 22LR.
Additionally, for CCW, unless you are recoil sensitive, a 38 snubby is just as concealable (if not more so because you can get hammerless or enclosed hammer versions) and is a signifcantly better all around SD round. Gives you a good excuse to get two guns as well!
One of the least expensive 22LRs, new or used, is Heritage Manufacturing's Rough Rider Combo
http://www.heritagemfg.com/. These are fun, affordable 22s that can be purchased new for $150 and used for about $100. Finishing isn't too good, but they are reliable and accurate. But as I learned first hand, the more complex loading and unloading sequence of a Single Action 22 can be intimidating in and of itself.
Then their are the DA 22s. Taurus makes their 94 in 22LR in 2" barrel lengths. Some members of this forum have good ones, but their seems to be so many bad ones (including one I owned) that I cannot recommend it. The Taurus 970 Tracker in 22LR is pretty affordable and has a better reliability record than the 94 from what I've heard. Ruger used to make their SP101 in 22LR; they can still turn up used from time-to-time.
I hope this has been of some use
.