The good thing about hip mobility, if that's the case, is that while there definitely is some flexibility in there to work on, it's largely strength also (heh, easier than flexibility). Look up wall squats, or maybe called wall facing squats. The idea is you stand with your feet a few inches from the wall, arms raised, and you squat. When her butt winks and she's all the way to the ground it should cause her back and shoulders to round which then causes her hands to touch the wall. So the goal is to do the exercise at a distance where she doesn't touch. When she gets a few sets of 10 reps out, she steps an inch or so closer to the wall. With perfect form, a trainer should be able to stand toes to wall and so a body weight ass to grass squat without their knees or hands touching the wall.
