Do you agree with Mamas decisions

This is, of course, a matter of personal opinion. The decision that Mama makes in the story is that she gives the family's hand-stitched quilts to Maggie, though Dee (Wangero) asks for them. Maggie is getting married soon to John Thomas, Mama says, and will likely get more use out of them. This decision outrages Dee who says that Maggie would not sufficiently appreciate their ancestors' quilts:

"Maggie can't appreciate these quilts!" she said. "She'd probably be backward enough to put them to everyday use."

Mama responds that she hopes Maggie will do just that, seeing the quilts as the ancestors intended—objects that are to be appreciated for how practical and useful they are. Meanwhile, Mama recalls that she had offered Dee a quilt when she went away to college but Dee then told her mother that she did not want them, for "they were old-fashioned, out of style."
Personally, I agree with Mama's decision. In the context of the story, Dee's fascination with quilting developed as a result of her turn toward Afro-centrism. We know this based on her style of dress—lots of "yellows and oranges," gold earrings hanging down to her shoulders, and bracelets "dangling and making noises"—as well as her new name, "Wangero," and her greeting, "Asalamalakim." Personal style, Mama narrates, has always been important to Dee, mainly to distinguish herself from her simple, rural upbringing. This attention to style often caused her to look down on her family, particularly her sister, Maggie.
Furthermore, Dee's opinions and tastes fluctuate over time. Maggie, on the other hand, embodies a constancy and faithfulness to her family and its traditions, which make her more deserving of the quilts.