As long as you find out why she is getting that B, you can work with her to get the grade up in the final. The transcript to college only has the final year grades.
On the other hand, I am very surprised to see the lack of discussions on HS class election. To get the highest weighted GPA, there are actually alot of work. Most of the school give 5 point for an A in AP classes. Naturally, most of the people know about taking as many AP as possible. However, few have gaven much effort to reduce those classes that get 4 point for an A.
Some classes could give either grades or pass/fail. You need to make sure you use the pass/fail because they don't add to the points.
You also need to find out the teachers. Some teacher uses very difficult curves, only a few get A in those classes. You need to make sure you can pick other teachers or delay taking that class to 12th grade. Because you actually only use your GPA of 9 - 11th for college application.
Ther are many other steps any family could take to get a higher weighted GPA. I welcome all discussions to help those parents and students.