Mine finally decided to arm herself after several local attacks on LADIES in this town a couple of years ago . . . that also motivated the sheriff to offer ladies-only classes (very well attended) that included firearms training! Once requirement? Bring your own handgun and 50 rounds of ammo! It took the sheriff months to train all who signed up, but I digress!
WHAT GUN IS CORRECT?
Like with guys, ladies like different things too so there's no definitive answer. So . . . I took 'em all, from .22LR, .32 S&W Long, .32ACP, .38, .357, .40S&W, .45ACP and .44 Magnum/Special.
Guns have to fit the hand well, plus the lady may have definite preferences.
Mine HATED the automatics! (Smart lady!)

She had trouble even working the slide on the little .32 auto (Kel-Tec P32), and felt she couldn't even rack the slide on the 1911 .45.
Turning to the wheelguns . . . she absolutely loved my 3" barreled Model 65 (though I put Hogue "goodyears" on it to soften the recoil).
Although "big," she also really liked my chopped barrel, custom 25-2 3 1/4" barreled N frame revolver in .45ACP . . . though it was too big to CCW. She also did her best shooting with these two fine revolvers.
So . . . I let her use my M65 3" for a while but found she still thought it too big and "heavy" to always carry.
ENTER HER FAVORITE HANDGUN! . . .
I found another 3" barreled revolver used in a local gun store . . . a S&W J-framed Model 37 "Airweight."
1. The Airweights have a frame weight of about 16 oz. with a 3" tube (vs. about 35 oz. for the M65), thanks to their small size and aluminum frame!
2. She could shoot that little Airweight well, due to the 3" barrel!
3. The 3" barrel kicked a whole lot less to her vs. my M37 snubbie too. Again . . . the longer the barrel, the less the recoil!
She's now found HER perfect handgun . . . and her Sheriff Department instructor told her she shot it as well as most cops at the range too!!!
Simple - Safe - Easy To Shoot - Accurate - Easy To Carry . . . that's a 3" J-frame.
T.
PS: Teach her to grip any handgun, and especially a revolver, with a high, firm grip. This places the barrel (bore axis) nearly as low as the hand . . . GREATLY reducing muzzle flip, torque in the hand, AND felt recoil. It will make ANY handgun easier and more fun to shoot well.
PPS: Start her with 140 grain target .38 Spl. WADCUTTER ammunition. The stuff is super accurate . . . and very, very gentle on the hand. Of course, eye protection AND hearing protection is an absolute must.