Mainly because it's veterans but the federal government is funding major help for homeless veterans. The population of homeless veterans has had a huge decrease in NYC, and on a national level has decreased 36% due to funding from the feds.
http://www.nytimes.com/2016/01/01/ny...york-city.html
This is a national problem (homelessness) and the huge reduction in the homeless veteran population underscores how this issue must have federal intervention.
So does the proper housing of the mentally ill. States have to work with the federal government on this.
http://www.nytimes.com/2016/01/01/ny...york-city.html