Make sure her name is on it asmany things happen to disappear in the NH's. You could at least track it down if it has your name and hers. Quilt the label right into the quilt so it cannot be removed.
Also, use fabrics from JoAnns or Walmart, where you haven't invested a great deal of money.

I made a quilt on commission once for a woman whose grandmother had just went into a nursing home. What the woman wanted for her grandmother was a memory quilt with pictures of grandma's husband and her children incorporated into the quilt. This would cut down the possibility of it being stolen! It also helps the grandmother. She remembers her children at the age they are pictured on the quilt anyway.

There is nothing wrong with keeping the scraps for your time. But maybe try and think that you are making the quilt for your husband's grandmother. It might make it a little easier to put in the time and effort.