Our food pantry takes them. If people have trouble paying for food they sure as heck can't afford incontinence products and food supplements such as ensure.
Here there are community centers that have meal and other programs for the elderly. I'm sure the ones in our city would be happy to have donated adult diapers.
Hospice is usually the reason people have boxes of diapers. They set up with a Medicare approved company to ship them automatically even when they still have some. I worked for a non-profit visiting nurse assoc. and we would get boxes and boxes donated. We ended up calling local NH to see if they could use them. This is one of the biggest expenses for a family that is caring for someone at home. See if there is a Homecare in the area and ask if they have patients that could use them. Medicare pays when hospice is involved but not otherwise.
I have seen diapers at a mission thrift shop. Also there are sometimes hospice resale shops that have medical equipment and supplies. You might google in your area. Area on aging might also be able to tell you of locations they advise needy families to go to.
This is one of the biggest expenses for a family that is caring for someone at home. See if there is a Homecare in the area and ask if they have patients that could use them. Medicare pays when hospice is involved but not otherwise.