This makes me wonder whether it might be helpful to distribute reusable items, or in the case of cloth pads, patterns for making your own. Menstrual cups have to fit closely, so they come in sizes, but cloth pads have a lot wider tolerance. Women who are crafty enough to make their own pads by ripping up old clothes for rags are probably capable of roughing out a slightly more detailed design that will work better -- and knowledge costs nothing.
So now all we need is to know whether a reusable option would appeal to women who are homeless or have been homeless. Since menstruation has been cited as one of the most miserable aspects of homelessness for women, and a reusable product would solve that problem about as well as it's possible to solve on the street, it seems like it could make a big improvement in people's lives. Women differ, though, and not everyone likes reusables. "Nothing about us without us" means consulting before deploying.