In our community there is “rental assisstance” for low income people.They have these homes in the project but if all these are rented -they will go outside the project and rent from private people w/ the samr restrictions. Here you can find homes for sale that advertise “seller will pay closing “ or partial pay etc. Some will say “no money down”. Your son may have an illness from some months back and not from each move. I would think that there would be mold in the house where you described the water is leaking. There was a tv show on about a $1,000,000.00 house like this w/ leaks and mold and finally they had to abandon the house.