Any of the calibers you are asking about would be great. I don't know if any one will be that much better than any other. I have my preferences like everyone here but I think you are on the right track. I know the .243 has killed many many animals but personally prefere at least .25 caliber for large deer just in case a less than ideal shot is presented or made. That said, it is still a good choice.
Like MagnumMan said, always use good hearing protection to minimize a flinch and probably more important than caliber is if the rifle fits her and she comfortable with it, not just, "I can make it work" but comfortable.
One more suggestion, a good recoil pad-ie Pachmeyer or Limbsaver. I have been shooting for quite a few years now and only in the last few realized the difference one of those two pads can make, they are awesome. I am not particularly recoil sensitive but am working on putting one of those pads on everything I have from .280 Rem to .375 H&H. I have nothing big enough to require those type of pads but they make shooting much much more comfortable.
Remember though, if you add the pad you might need to cut down or have the stock cut down or you will lose the fit the gun originally had.
My opinions sir, good luck to you and your wife.
mnimrod45
