Who in matrilineal societies with Crow kinship, sisters remain close to one another throughout their lives?

I don't know who is asking you this question and therefore I don't know what answer they want. Many cultures are matriarchal which means that the eldest female in the family group pretty well rules the roost. The Cheyenne were certainly like this and so were the Cherokee. The families would relate to their female kin, so when a man married a woman, he would move to her clan and kinship rather than staying with the father's group. I would think that the answer your teacher would want would be Omaha