She can't spot reduce - she can lose fat from all over, eventually from her stomach.
As far as what she can do - NUTRITION is the MOST IMPORTANT thing here. Then training - she needs to train right, and I don't mean endless cardio! If she doesn't already lift weights, then she needs to START.
Get her to review the article Transform Your Tummy With These 8 Tips!, and then have her read The 3 Keys to Fat Loss for comprehensive advice and information on nutrition, supplementation (only the basics, and she doesn't even need that, honestly), and training for effective and successful fat loss, and apply the principles there.