The rule of thumb is to use only 100% cotton in the top and backing of a quilt. It wears well, stitches easily, and can be washed. But there is always an exception to every rule, isn't there? Perhaps you have seen Crazy Quilts. They were meant to be decorative, like over the back of a sofa or across a piano. Victorian ladies used silks, satins,velvets,laces, etc.. If your mother had any special dresses, and liked frilly things, then you could use them, and just know that you could not wash it(perhaps dryclean every so many years.)
God bless you & your family. I lost my mother December 12th. It takes a bit to seem real. But a quilt from her clothes would feel like a hug everytime y'all wrapped up in it.
Good luck. Debbie