Lose it slowly. Most dietitians agree more than 2-5 pounds a week is unhealthy and more likely to get put back on. The first 5-10 pounds are most likely water weight anyway, although its exciting watch it come off so fast, lol.
I find making lots of healthy snacks ahead of time helps, especially when packed into appropriate servings. I have celery/carrots/sweet peppers and pretzels normally packed up.
If she's looking for a program she could try going to the Slim Fast website and requesting a startup kit. They also tailor meal plans, and it only spans 12 weeks, which isn't too daunting, even if you have to start over.
https://www.styleyourslim.com/