Why did Dee leave home in "Everyday Use"?
Mama says that, several years ago, she and the church raised the money to send Dee away to Augusta to school. This was shortly after the family's first house burned down, some ten or twelve years before the start of the story. The possibility that Dee actually set the house on fire exists because she was already outside when Mama ran out of the house with Maggie (who'd been badly burned). Moreover, Mama recalls "a look of concentration on [Dee's] face as she watched the last dingy gray board of the house fall in toward the red, hot brick chimney. Why don't you do a dance around the ashes? I'd wanted to ask her. She had hated the house that much." The fact that Dee was known to hate the home, to be so ashamed of it, and that Mama describes her as "burning [them] with a lot of knowledge [they] did not need" (just as Maggie was burned by the fire) makes it seem as though it is at least a possibility that Dee set fire to the home. We might suspect, even, that this is what ultimately prompted Mama to come up with the money to send her away (though she only says that Dee was sent away to school after the house burned). At the very least, Dee leaves home, ostensibly for school, but perhaps more likely because she was so miserable (and, maybe, dangerous to them) at home.
Dee left home so that she could venture out and find her true "identity." She felt so helpless growing up in such an impoverished home. She was popular, outgoing and also pushy. She disliked her home and was ashamed of her family. She was hoping that going off to college that she could assume a new identity. She does this by changing her name and meeting other friends--such as her boyfriend, Hakim-a-barber. They come back to her mother and sister's house to obtain some of the cultural items around the house to "show off her heritage" at school.