Any firearm is better than no firearm.
The larger the caliber, the better.
The argument the 9mm, .38, .380 rounds are just as effective as .40, .44, 45, etc is silly. No, all rounds do not kill at all times.
But if you know a bad guy is coming though the door and two firearms are on the table next to you, one a .38,9mm,or .380 & the other a .40, .44, or .45, which will you grab?
But again, the weapon did the job. She and her children are safe.
“A free people ought not only to be armed and disciplined, but they should have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government.” ~George Washington
US Coast Guard 76-86 Semper Paratus