Well I think the intention of the author was to capture the growth of Selina and how she fought to be different from her mother. However, Selina admired she mother's strength and how she endured and overcame. Selina in turn took on the same strength that her mother had and nothing else. Their relationship throughout was strained and it definitely didn't get better with the death of her father.
the Mother daughter relationship is pivotal in the coming of age or bildungsroman novel, usually in the bildungsroman novel the daughter leaves the mother to learn; to come of age, as it were. in Browngirl BrownStones the daughter leaves at the end of this process, leaves after she has come of age, right under her mothers roof. The love hate relationship of Silla and Selina, this mother and daughter is Marshall's way of discussing the themes of family acceptance of difference, family love, family healing, especially of 'self ' inflected family hurt