If available I would have her swing a 32/20 or a 31/19 for practice purposes. Put a concrete block behind back foot like Howard said.
Either put the tee on a bucket or use an instructo swing top tee. Have her do the matrix ( slo-mo drill down to impact.)
Ball will be located at top of strike zone. Have her slowly come to the ball without hitting it.
Look at her alignment. elbow higher than hands, hands higher than barrell of bat. Is the sweet part of the bat on the ball.
My guess would be no, so bring her hands tighter to body on rotation until the sweet part of bat lines up with ball on the slo - mo swing down to impact.
Once this is achieved and a visual is in her head, hit some. I think you would like what you see.
Her hands stay around her back shoulder on rotation which is good and most girls have to be taught this as to not get ahead of rotation with hands and arms. Once her hands have a tighter path, she will be close to connection.