I hope this doesn't come off as critizing you, but wheather or not you buy more fabric than is needed isn't the point. buying what is called for in the pattern is fine. This is your husband's grandmother you are making it for, not your mil, although she suggested it. Having my mother in a nursing home 2 years before her death was hard. She didn't know us, but some people in nursing homes become attached to "things", a quilt, a teddy bear, a doll and even if they don't know who gave it to them, it, for some reason, is dear to their heart. Putting her name on the quilt is a must. taking it home to wash maybe a problem, unless there is family member right in town. Items in nursing homes may needed washing more often then they would at home. Make it to go through a lot of washings (like a baby quilt), make it with all the love you can put into it and it will be cherished for many years to come, if not by Grandma, then by your mil and your dh. God bless you.