Among the recordings available at Spotify, all 8 of those by MJH are consistently called "Richland Woman Blues," while on MJH tribute albums, 2 out of 3 instances have "Richland Women Blues." Among recordings done by others but not on tribute albums, 21 out of 26 are called "Richland Woman Blues."
I have heard one live recording in which MJH introduces the song himself, saying: "This is the Richland Women Blues." Within the song itself, he sings: "The Richland women says....".