I would do a simple patchwork. After all, if they have given you so many different materials, then they probably are not quilter themselves. This means, that in order to keep your work load to a reasonable amount, the pattern should be easy and yet show off the material from the clothes.
Since they obviously don't know what is appropriate, don't try to use everything. They've given you your choice. I've had plenty of success in using 50/50, but only wovens. I've not tried to use a knit nor do I have any desire to do so. In fact, I just threw away 3 big bags of double knit pieces that someone gave me because I couldn't bear to touch the fabric. I decided to not become someone else's dumping ground and then feel guilty for not wanting it.
However, if you were close to this lady, then make them a simple quilt. They will treasure it. If you have lots of scraps, then make a simple patchwork, maybe putting them on edge and making it look like diamonds. You could make the dreaded piano border from blends. It would use up a lot of fabrics and make it colorful and scrappy. If I were the family, I'd love it because it would be many different fabrics.
Then, I'd take the scraps from those things you don't use and donate them--whole sweaters/tops to Goodwill or SA and partially cut up knits and dump them in the dumpster. I'd not mention what I did with the leftovers to the people who gave you the bags of clothes. They have enough to deal with and were probably glad to get rid of the clothes in the first place.