XR100, TTR125, then depending on whether she/you/dad thinks she can handle a 2-stroke, KX, RM80's (power-valve models, 98+ for the KX). I take it she'll be riding trails with the two of you? Get her to check out the sizing at a local bike shop to see which she's most comfortable with and take it from there.
The one thing to keep in mind is the fact that she'll have to learn clutching after the PW80, so depending on how stubborn/interested she is, two strokes may not be the way to go (for the moment). I love my two strokes and learnt to ride on them, but it was a struggle and often thought I should be on a four. But I'm extremely stubborn, so have kept with it (never mind the times the bike's been up for sale in my mind).
Let us know what you decide on (or rather what she does). How's your dad after his last accident?
Michelle