Like others have siad..for home you can't beat a pump shotgun. If you even think there is someone in the house racking the slide does one of two things. 1. gets the to speak up and let you know who/where they are. Or 2. Gets them on the run out of the house. And if they go for option 3. you don't have to be very acurate to put them down with buck shot or a heavy bird shot.

For concealed carry I have a Taurus PT140. Its a 10+1 with .40 s&w. Great concealable gun. A revolver is also a nice choice for safety. My dad owes one of the Taurus Titanium 357 mags. 7 rounds (or six with and open under the hammer) very light almost unnoticable. Very nice. But recoil is hard.

Whatever it is have her shoot and get comfortable so shooting is second nature and so she handles it safely too.

Good luck.