B/X is prominent, so that tends to be the default assumption: of course your PCs have to be made of tissue paper and have few/limited abilities because that’s how you induce (various elements of OSR play). I don’t think that has to be the case.
If you’re open to suggestions, I’d proffer Worlds Without Number. It has B/X roots, but it also takes elements from newer editions. PCs are much more robust (and capable), but it’s still manages to evince the OSR style.I think for her, and some of my other players, a stripped down, fast playing D&D/OSR would be fine as long as you didn't feel super weak. For example, she loved HeroQuest when I introduced her. Something like that in a D&D form would be a hit with her.