I received a quilt made by my grandmother. She took all the polyester fabric that my mom gave her and made quilts for 6 different people that year. She backed mine with cotton and a polyester batting sandwiched between. She tied the layers together with yarn. I have had this for 20+ years and at one time it was on my bed. It is now a quilt that we use during the winter since it is very warm. There is one square that was not of the same kind of fabric that is wearing thin and the seam on the side (backing brought to top for binding) that has let loose in one spot. Other than that it looks really good for its age. I may not be a polyester fan, but I would not give it up for the world.
What every you decide to do with the top, it will be wonderful. I would also show her what you did and as part of the conversation, mention to her that she could have it if she wants. Have fun and enjoy the process.