Social Security. Unemployment insurance. WIC/SNAP (food stamps). Government mandates affordable housing on major transit lines. Non-usurious Government loans for the working poor, secured against income. Stuff we already do, but should do more.
I think one of the keys would be allowing people to live in improvised housing, a la Brazilian favelas. Loosening or repealing housing standards and property would reduce stress on these people. e.g. let people in bushes or trailers without forcing them out.
second, receiving mail was listed as a problem. how to get people their mail for important papers?
third, allocating land for farming their own food. why should they have to take part in the rest of our food economy if they can't fork over $1.25 for an apple? Just let them tend trees with their time.
fourth: transportation. often you have to get someplace. how can we design public transportation so it gets the poorest where they need to go reliably?