The central conflict of Alice Walker's "Everyday Use" is complex. The narrator/mother and Maggie represent traditional black women and family, what they in fact are. Dee represents what some think black women should become. As such, the mother could be considered the protagonist and Dee the antagonist. The mother decides the conflict when she stands up to Dee and insists that the two heirloom quilts should be kept for Maggie as was promised. Maggie, in the mother's view, is more deserving. She will put the quilts to "everyday use," not display them as a sign of her heritage as Dee wants to do. The mother and Maggie have dignity in their own right.
I'm afraid I cannot really comment on the foil in the play. I don't really see one. You could say Maggie handles herself as one should and Dee does not, but they are so naturally different a case for Maggie being a foil seems to me to be a stretch.