In this poem the word relief is used in the line the "Millions on relief today." Langston Hughes doesn't mean the removal or lightening of something oppresion, painful, or distresssing . He means the relief that today people would call welfare or food stamps. Back then they would call it relief because it did bring relief. So the line means the Millions on welfare today.
Source:
The Webster's Dictionary
http://www.m-w.com/cgi-bin/dictionary