I'd suggest you to come up with a high protein low caloric diet for her. Try to aim for something which is doable and not extremely restrictive. You know, the most important thing for a successful diet is to be consistent and, ultimately, change habits.
When developing a diet, keep in mind that a caloric intake of less than 1200kcal/day (for women) can lead to lean tissue losses and lower metabolism, things you definitely want to avoid.
I'd also suggest you to disregard cardio, unless it's something you or her really enjoy doing. People who do cardio tend to eat more after exercising. And in order to lose weight, the one thing that matters is a caloric deficit by the end of the day.
Weight/strenght training is a great choice for changing body composition as well. When creating a program, try to focus on the main composite movements: squat, deadlift, bench press, pull-up... Look up every movement closely so you can learn how to perform them correctly and with good shape.
If you want to look further into the diet/workout subject, I'd recommend you to look up articles from Alan Aragon, Martin Berkhan or Lyle McDonald. Or you could just check Ian McCarthy's videos at youtube