Yoga, I am the same way with cramps and I swear by yoga when it's my time of the month! The stretching really helps and actually reduces PMS as well as cramps! Here's a couple of simple poses she can do to help relieve it.

http://www.yoga.com/ydc/enlighten/en...ga and Periods

Start with this pose
http://www.santosha.com/asanas/shava.html]Shava-asana

http://www.yoga.com/ydc/enlighten/en...addha Konasana

http://www.hathayogalesson.com/]The ...ing Side Twist

http://www.yogacircle.com/asana_menses.html]Asanas

Hopefully this will help, also there's a tv show you might want to look for called Wai Lana Yoga and she has episodes on tv for Mentrual Poses.