Answer: I would contend that the right answers are A) Mira is more mature than the other kids in the group and B) Mira is acting like a leader for the group of children.
Explanation: Just to elaborate a little on the answer, it can be added that the narrator is describing her as "motherly," and he or she relates how, anticipating a fight, Mira intervened timely and helped the children play joyfully and safely, without any complaint from their part. This indicates that she was more mature than the other children and that she acted liked a leader for them—who seemingly accepted her leadership.