Please accept my sympathy for the loss of your mother. Not that I'm all that organized, but all my quilting fabrics are folded with a 4" ruler, then put into the appropriate drawer, according to the background color and stood on it's side, so that I can see a portion of the fabric print. The non cotton fabrics are all in large plastic totes, sorted by the type of fabric, fleece, upholstery type, etc.
I think what I would do is to go through the fabrics, folding as you go and decide if you want to keep it or not and do the same for the rest of the items. I used to sew clothing and had tons of zippers, which I had sorted into large zip lock baggies according to size, I did the same with elastic, seam binding, etc. I would do more or less the same with the craft supplies, like paint. I would check the paint to make sure it's a good bottle, since it tends to dry up after a while, even when it's shut tight. Whatever you decide you aren't keeping, donate that to a local charity, school or the like or have a yard sale. But, if you don't do a lot of garment sewing, for example, then I wouldn't keep most of the stuff. I have my threads sorted by color in the small plastic totes, the 100% cotton thread are separate from the regular thread by color also.