I'll let others recommend bullet choices........
I'd take the off season and work with her and her fear of recoil. Make sure the scope she's using has enough eye relief. Check and confirm her shooting form and that her hold allows for the recoil at its minimum feel. Purchase a PAST recoil pad, which WILL help with the felt recoil on her shoulder. Keep her shooting all year.
IMO way to many hunters worry or are afraid of recoil, when learning to absorb recoil, even very heavy recoil, never seems to be something they are willing to learn or attempt. Its all in positioning the rifle properly and the form when holding. There are many tutorials online and videos that can help.
I have a great niece that when very young, became extremely interested in shooting and hunting. With no disrespect intended, just no other way to say it, both her father and grandfather taught her everything wrong and she became recoil shy. One summer they came up to spend a few days and of course she wanted to shoot. We started with an LT20 and the target thrower. Instantly I noticed she was doing everything wrong, like standing straight up as an example. After a few minutes of instruction on her form and hold, she not only felt better shooting, she started busting birds like crazy. She went through 5 boxes of shells before I called it. And OH NO, she wasn't done. She graduated to shooting my Encore with a full charge, then to the 30-06! It was all because of the things she was doing wrong in the beginning, that was changed in a single day's shooting with a little instruction. By the way, she weighed less than 100#'s and I don't believe she weighs over 110#'s now. She currently owns and shoots .45 pistols, revolvers, a 12ga Rem. 870 w/slugs, and AR platform rifles. Oh, I dare not forget she's an archer too!
Point is, help her with her biggest obstacle, which is her fear of recoil. Work on all the contributing factors. Once she masters that, she may just out shoot, and out hunt you :yeah: