She turned 82! Weeks ago! and you are just now letting us know! How old are you?
Just kidding.
I hunt whitetail with my Colt 6920, iron sights, around 25 - 100 meters max. I have never had a deer run more than a few meters. I always aim chest center mass and spend a few days at the range zeroing on the ammo that I will be shooting. Any hunting round or self defence round will work fine. It is shot placement. Though I "feel" that the heavier rounds had a flatter trajectory and was more lethal because of the consistant shot placement at different ranges.
With a lower caliber round, weight shouldn't affect recoil much. Just zero in the same conditions that you will be hunting, early, damp, cold, ect. Have her shoot targets at different ranges and see if she understands where to aim.
Recomendation, have your gun out there too and be ready to make a follow up shot. It's not fair to let an animal suffer.
Good luck. Great to hear about your trip. My daughter is 6 and will be starting to shoot with me soon.