First off, she's not in the correct start position. Look at the position of the shoulders and arm angle. Can't tell if the rest of is okay from this angle - eg bar over midfoot, knees pushed out. Fix this first.
The Deadlift - Demo and Teaching Method Videos
An incorrect start position isn't helping her hold her back in position, it's likely making her bad physical habits worse.
Can she tell that she is fucking up? Is she doing this with warmups? Squeezing slowly off the floor - extra slowly - on the warmups can help her learn what is right/wrong.