You need a minimum of 2" more on all 4 sides so your batting and backing should measure at least 61" x 74". If you are buying prepackaged batting, a twin size would do. If buying batting by the yard, 2 yards of 90" wide batting will be more than enough. I find that wide quilt backing fabrics or wide muslin is less expensive than regular 42" wide cottons. If you buy a wide fabric backing, 2 yards will be more than enough. I like to use old sheets for backs if I can find one in the right color, do you have a Goodwill or other Thrift Shop close to go find a sheet for a couple of dollars for the back??