(What I discovered in the end is they wanted a bed spread not a quilt. It is HUGE)
This is my story too. I have made & quilted for 2 friends and will be more particular in the future if asked again. Both bought the fabrics and one top was half done, but she chose drill for the front and back and it is darned heavy. I still have to put on the binding. The other ended up around 115 x 115 and had to have the pillow sham as well. To top it off the lady bought very thick poly batting - which I had said not to get - it was too thick to quilt the whole thing on my Tin Lizzie so had to be turned to finish the last 30".
If you want to do this and are not getting paid I would make something easy and as small or large as YOU like.