Helping her problem solve will be a huge benefit in practical skills and the resilience learned. I'd brainstorm with her things she can do to avoid the girl and how she may be brave enough to respond (with nonviolent means). How can she show that her happiness isn't dependent on what others think of her? She can make and have friends without relying on those influence by this girl. There's a good accronym for dealing with bullies.
STOMP (out bullying)
Stay away from bullies. Avoid where they hang out. If in the same class, ask to sit as far away from the bully as possible. When it's not possible to stay completely away, ignore them. They want attention and you can't bully someone who doesn't pay attention or care what a bully thinks.
Tell an adult. If you've tried to solve the problem yourself but can't, tell an adult IMMEDIATELY. Don't wait to get home to mom & dad. Talk to the teacher, recess duty or whoever is closest when it happens.
Offer help to others you see getting bullied. Chances are this person is mean to others too. If bystanders and good kids show the bully that they will stick together, they'll get the message this is unacceptable behavior. Tell the bully it's not okay to be mean & go with the person to get help.
Make friends with lots of different kids so you aren't relying on the bully or those they have convinced to be their gang for friendships. Other good kids can see how they treat people and will want to avoid them too.
Project confidence. Bullies live to intimidate others. If you're confident in yourself and show that they can't shake you, they'll get bored and move on. In fact most bullies. will never even approach someone they can see are confident in themselves.