What sort of riding are you & your wife intending? Trails? MX? HS? Trials?
From what bikes you're listing, I'm taking it trail (for starters ;))
See if she can handle the XR80 (or even 100) instead of the 70, slightly bigger wheels (better), "auto" clutch (at least the way my friend's daughter rides hers lol j/k - nah, she's getting the hang of it) and it'll make the transition to a "full size" bike easier as your wife "outgrows" it - meaning a slightly larger bike once she gains more confidence.
One person who'll be able to help (if she's got time) is CJ Rider - your wife is taller than CJ by an inch. I'm pretty sure CJ had a TTR125L before she got her Pampera before she got her KX100, but what she had prior I dunno. CJ's not around much at the moment, so be patient if you do contact her.
Be aware though, if/when your wife gets addicted, she will be moving up but will have hassles finding the perfect bike. And those of us 5'0+ think we have hassles.
BTW, FWIW, my 11yo friend loved the KLX125, but then she's been riding since she was about 5/6 so isn't quite so uncomfortable on taller bikes (you've got me thinking about how tall she is, and I'd guess she'd be about the same height or a bit shorter, but again, she's been riding half her life so has some confidence).
But definitely, get as big a bike as your wife can handle (and I'm definitely not meaning a full size bike, I'm meaning in the XR/TTR/KLX/DRZ "kids" bike range) as the bigger wheels do make it easier for uphills etc etc - but make sure she can pick it up when she dumps it and can restart it.
Good luck & let us know how it goes.
Michelle