What have you tried?
Have you tried leave in conditioner? This works great in my hair, as it can be very frizzy without it. Does she have curly hair or is it more poofy? I have poofy hair but used to perm it to make styling easier. I wouldn't suggest that, but maybe some sponge curlers once in awhile to sleep in might help tame it.
Also, what kind of pillow case does she use? I silky one is better for frizzy hair.
But I stress tiny bit. Too much and my scalp hair looks greasy and matted down. But my ends look normal.