Since your gran picked out the fabric for her quilt that she wants you to make for her, I'd have to think that those are the colors she wishes to have in her quilt. You don't have to love it, but it appears your gran will, and I don't think there's anything wrong at all with monchromatic quilts. In fact, they can be down right gorgeous!! Just my humble opinion. And that bright green floral will sing loud and clear!!!