My late MIL was a peach and loved anything I made for her and everything we did for her, or even if we just visited with no gifts. I was very fortunate to have had her for a MIL.
Reversible quilts have been around for a long, long time. I was gifted an antique quilt the other day that was reversible. If you're making one side in browns and blues, and plan on making another top to put on the other side, why not just ask her what colors she'd want? Personally I'd just make two quilts. Maybe she'd like somthing in Spring/Summer colors.