Both option B and C are correct as they are the same.
T<u>he line means that the friend was in the attendance along with the mother and the sister of the narrator</u>. This can be deduced because in the sentence the friend is mentioned separately from the family to differentiate her from them.
<u>So when hello is said to a woman, who could be either of the three it can be deduced that it is the friend</u> being talked about as she was differentiated from the others in the previous sentence.