Selecting a gal's big game rifle can be a bit of a balancing act. The rifle must be light enough that she can carry it all day without undue fatigue, yet its recoil level must be such that she doesn't get pounded when shooting it. If you're a handloader, any modern cartridge can be loaded to suit her and the application it must fulfill, but if factory ammo is all she has access to, the cartridge choice needs to be on the moderate side. To my way of thinking a 6.5 cartridge, either a 6.5X55 or a .260 Remington is the logical starting point, as those smaller don't have the bullet weight to provide optimum performance on really big game. Yes I know, 243s have killed moose, and I know the math, if one shot is insufficient then shoot again, but to me there must be a reasonable expectation of a one shot kill; the 6.5 has it the .243 doesn't. The quarter bore fans correctly make the argument that only .007" separates the .25s from the 6.5s, but in traditional bullets there is a world of difference between a 120 gr bullet and a 160 gr, and in premiums there is a world of difference between a 100 gr bullet and a 140. The other two cartridges you might consider are the 7X57 and the 7-08, both have a long history of excellent performance on game and mild disposition towards the shooter. If you are a handloader then I would suggest a .270, .280, or a .30/06.
So much for cartridges. The key to success is the selection of the appropriate rifle, not so much the cartridge its chambered for. The rifle is easily fitted to her if it comes with a wood stock, which in this case she prefers, so its win win on that score. A high quality recoil pad needs to be installed, and the rifle should be fitted to her when she is dressed as she would typically be while hunting. Keep in mind that the rifle if a tad too short is easier to shoot then one that's a tad too long. Fully equipped with a sling, scope, and rounds in the magazine, it would be nice if the rifle stayed under 7 pounds, my wife's commercial Husqvarna 1600 carbine in .30/06 is closer to 6, but she prefers a ghost ring and post to a scope, and typical .30/06 recoil doesn't upset her. When youngsters come around to get some marksmanship instruction, I load 125-130 gr bullets to 2600 fps, which is mild in both blast and recoil, yet they are accurate out to 300 yards or more and are suitable for the smaller species of big game. My nephew has killed his BC mule deer with a 130 gr TTSX loaded to 2600 in his .30/06.
A much over looked piece of equipment these days is the sling, specifically a shooting sling that can double as a carry strap. I highly recommend the Safari Ching Sling from Galco. It provides a wide contact area over the shoulder when used as a carry strap, yet is is quick to put to use as a shooting sling, and greatly improves a shooter's chances of a first round hit. I like to mount the front swivel stud on the radius of the forend tip, as thus situated the stud has no way of cutting the hand when the rifle recoils.
Here's a few pics of our grandson doing some shooting with my wife's '06 Husky. The LOP is 12".
The sling here needs to be positioned higher on the back of the arm, and could probably stand to be a bit tighter . . .
This is a better sling position . . .
With the Decelerator pad and correct LOP, shooting an '06 prone is no problem . . .
The forward positioned sling swivel on my .375 and .458
