Here's a suggestion .... and it may seem off the wall at first. There are two cartridges not mentioned by any of the others. These are the 260 Rem. ... which is a 308 Win. case necked down to 6.5 mm; and the 6.5X55 SE ... which is a popular cartridge in Europe for medium game. I can attest to the effectiveness of both of these on white tails and mule deer. I do not have a recoil chart in front of me, but I am guessing that the recoil is something just less that the 7mm-O8 Rem. Both of these cartridges usually do great with bullets in the 130 - 140 gr. weight. There is not a whole lot of choice for ammo in either, and it would probably be impossible to find a box in Two Dot, TX or AR or AZ , etc. I have a European Mauser in 6.5x55 SE and I have killed dozens of deer with it, out to well beyond 250 yards. It is my No.1 "lender" and the "spare" I bring with me. One of my best friends son has used a 260 Rem. for going on 6 years. He has killed many, many deer ... a few feral hogs ... and 2 fine mule deer.

Back to answering your question .... look at a youth size rifle in 270 Win. I love the 308 Win. It is my No.1 personal choice , but in your case the tad lighter recoil, and the fact that the 270 Win. is one of the best case-bullet combos for deer killing .... if she can handle the recoil, can't go wrong.