I do believe those are correct.
Mama's decision to give quilts to Maggie has a development on the plot by creating the rising action. Mama can see that Maggie really wants and deserves the quilts.
Hope that helps you
Hypothesis is a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation. Theory is a contemplative and rational type of abstract generalizing thinking or the result of such thinking. Apparently, if the hypothesis is proven it would become a theory.
They are definitely not synonyms, that would mean they mean the same thing wich they definitely do not. They are antonyms.