I've been anemic off and on most of my life. I lack the ability to absorb iron through food and supplements at the rate that average people do.
I'm assuming your friend is a teenage female. If so, she can be a successful vegetarian, but she will have to take care to ensure that she eats properly.
In order to get the 25mg of iron daily that she is required on a vegetarian diet, her diet will have to include lentils, beans, lots of green vegetables, nuts and seeds.
Try suggesting to her to have at least 1 vegetarian meal daily. That way, she can find some foods that she likes and learn about nutrition at a slow pace. She already has a medical condition that can often be prevented and corrected with proper food choices. She needs to learn what those choices are.
Feel free to ask any questions for her or yourself and we'll all do the best we can to help you on your journey.
EDITED for typos