There is a lot of good suggestions here. With any problem regardless if its aviation or not is to identify what the root is. An earlier post suggested that your student describe her thought process and ask why after each one. How else are you going to find out if you don't ask..right?
Generally speaking, and i'm only saying generally, females will vocalize their fears and be far more descriptive than males. I was a fine example of this during my primary training. Departure/power on stalls where always a time of white knuckle flying for me. I hated them. I had no problem doing power off stalls but as a student I never took the time to figure out why the issue. Since I wanted to be a tough guy in front of my instructor, I kept a pretty mean poker face and never expressed the anxiety I had.
Later on I finally figured out what the issues were that caused my anxiety...If your student is only having difficulty with power on stalls perhaps this could help.
1. When entering a high angle of attack, I'd lose the horizon and I would have a real difficult time feeling when the plane started to turn left. After I'd realize the plane was starting to go left, I'd panic and get a flood of anxiety. My eyes were rolling around in their sockets like a ball in a pachinko machine. I'd be wondering are the wings level, is the ball centered, the stall horn is blaring and airspeed is going down. A lot of stress in a short amount of time when things are happening quickly. It was burned into my head that an uncoordinated stall will get me in a spin and I would die.
The solution was to focus on a cloud if available and to really scan & interpret the AI and TC as a backup. During my primary training the skies were usually clear with no outside reference available. As a student I was focusing on the clear blue hoping for a nice coordinated recovery. I should have been looking at the gauges primarily.
2. I'd be very light on the controls. I'd pitch up but not in a very authoritative way. In essence, I was prolonging the inevitable. The engine would be screaming at 2500rpm and it would take forever to get the plane to stall. This would allow plenty of time to let the anxiety build up.
The solution for me was to continue to pitch back and maintain that desired pitch angle. What I would do is pitch for the desired amount initially but I wouldn't hold it there. As the elevator became less effective at the lower speed, it would take forever and a lot more back pressure to get the deed done.
Pay attention to her if she is allowing one of these things to happen...if all else fails, I'd me more than happy to have a lil heart to heart with her