I would sort them first. Were they mine, I'd cut 2½" strips. Sew together 6 strips alternating dark and light. The mediums could be either dark or light depending on its neighbours. Then cut the strips into 2½" strips again. This gives you hundreds of little six-in-a-row squares (strips). Now you line up these new little strips from different stripsets, again alternating dark and light squares and sew together six strips to make a block of about 12". The blocks can be attached to each other with or without sashing or you can add some picture blocks or strips. Since the fabric represents clothes you both wore, it will take her on a trip down memory lane. You could also use short strips and even single 2½" squares if the pieces are smaller.
Would love to see how your quilt turns out. Enjoy the process.