The above suggestions about food are very good advice.
As far as exercise goes, she'll just need to remember that exercise has an insulin-like effect- the strength of which will be determined by the duration/intensity of the exercise.
So, she'll have to use trial & error to find out what pre-exercise meal gives her enough fuel for a workout, when she needs to eat during a workout to sustain her bg (usually maltodextrin is a good option for sustained aerobic activities >1hr), and what does well for her afterwards to keep bg from getting too low. It will take a lot of poking at first, but once she establishes a routine, she'll probably be able to control her bg and insulin needs with diet and exercise.