I'm so sorry for your loss - I don't know if I'd ever be able to do a project like the one you are contemplating.
Maybe you can start by making rectangles of all the bibs - either cutting them down or adding sashing/strips around them to make them more manageable.
Or by sewing the bibs on to a piece of backing like you would applique something. (Sort of like the Sunbonnet Sues, but these could be Bibs worn by Beloved Grandson) If you used different colors of backing, you could get some color in the quilt, and make the pieces a bit easier to handle.