Yes, I strongly agree that the government is responsible for the betterment of slum dwellers. Although some argue that they aren't tax payers hence , the government isn't responsible for them. However, when those people can't even manage two square meals a day, how on earth will they pay taxes.
The government is there to work for the betterment of people, irrespective of their class , status or anything. There fore its the responsibility of the government to arrange housing facilities for these less privileged people too.