Gail,
My heart aches for you. I have lost both my parents as well, but it was 33 years between them. My Mom passed away almost 4 years ago and I miss her more than I would ever have imagined. Your family will understand if you don't get the quilts done by Christmas. They will treasure them whenever they get them.
As for the rag quilts, I have even used inexpensive blankets from Walmart as the middle batting. I could not tell a difference in them and the cotton batting. Just make sure to get soft blankets, not rough feeling ones. They have been washed many times and still look great.