First, I'd advise you to sit down with her & really talk about her concerns/defense plans. She needs to know & understand the use of force laws and, more importantly, be able to use lethal force in a critical incident.
If she can't devote the time, $ and/or resources or won't use lethal force against another human being DO NOT buy her a firearm.
Also, let her rent or shoot a few different models. If she can't operate a semi auto pistol or safely load/unload/fire a DA only revolver then she isn't ready for a firearm. It sounds simple but many people can't safely work a slide or pull a DA revolver trigger.
If she does want to get a new handgun or buy a weapon & meets the criteria, I'd suggest a simple DA only snub revolver in .38spl. A Ruger LCR, a S&W model 638 a 442/642 or a 649. She can buy a Blackhawk SERPA J frame holster & add a CT lasergrip. For defense, .38spl +P or .380acp is the lowest I'd go. I'd also advise her to only use factory made ammunition for home defense no reloads or hand-loads. Her safety & well being are no place to go cheap or cut corners.
Encourage her to take a safety class & learn proper tactics.
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