Actually, the row house structures are awesome. A lot of quality, character and charm under all that crap. New "decent low income housing" would cost much more and the quality much worse than renovating the existing structures.
But again, it requires actual work and not just throwing money at it hoping something happens. Get Habitat for Humanity and a few other non-profit groups together and start sweeping and cleaning out, replacing roofs, rotting wood and mechanicals as needed. Knock out a block every 4 to 6 months. Then the only problem would be training the IPs on how to use trash cans, brooms and kitchen & bathroom cleaner. Oh yeah, and teach them how not to do drugs and kill each other too.
If the foundations are good and walls are sound then run an apprenticeship program using locals. That way they can learn a trade and buy one of the houses. Electrical, plumbing, drywall, carpentry. Good jobs and good prospects for a decent life.
If you don’t first exterminate the rats and other vermin, they’ll just move into other areas, and eventually return and infest the upgraded housing.