best way to decided what gun will work for you, is to go to your local gun range and rent a few guns. Rent the basics and decide the caliber that fits you and everyone in the house hold. Teach everyone in the house how to safely inspect the gun for live rounds when ever they touch a gun. Start with a full size handgun, and for someone new to guns I would start with a double action only. Single action guns tend to have a lighter trigger pull then double actions. I prefer the .40 caliber round, the recoil is manageable and has great knockdown power. Reliability is a must! If you have doubts in your firearm, it becomes worthless.
There are tons of great guns on the market, but these are the most proven guns that can be operated and trusted by everyone in your house.
Double action only
Glock 22
Double action / Single action
Sig 226