I too am sorry for the loss of your Mom. I have made quilts for a friends sons out of Dads jeans and shirts. I used flannel on those as they were rag quilts. The shirt weight had to be paired with batting to make the weight closer to the demin and flannel weight blocks.
My girl friend and her sister used quilting cotton on theres for their siblings. They cut 2 1/2 inch squares of Moms clothing then surrounded them with quilting cottons to make up a 10 1/2 inch block as they are a large family and had lots of quilts to do. As others have said, its your quilt, do what works for you. God Bless.