Like many of the others above, I suggest a .38 Special revolver.
You don't need anything small and light, because you won't be carrying it concealed. So, a medium sized weapon with maybe a 4" barrel should work fine.
Many women have trouble with semi-automatic pistols because it can be hard to load the spring fed magazines and hard to work the slide to chamber the first round. The revolver avoids all that.
A revolver is easier to understand and use than a semi-automatic pistol.
And .38 Speical ammunition is easy to find and less expensive than most.
I wouldn't worry about getting something that will shoot the higher pressure .38 rounds or the .357 Magnum. The recoil will be heavier, the weapon and ammunition will be more expensive. And my opinion has always been that just by owning and knowing how to use a firearm, you will have mitigated the risk enough.