Moses has been out of action since February 27 with a thigh strain, while an ankle injury has kept Valencia out since February 13.
West Ham have been dealing with a defensive injury crisis in recent weeks, with Cheikhou Kouyate, Michail Antonio and Reece Oxford forced to drop into the back line.
But Bilic said: “Victor Moses, Enner Valencia and Joey O’Brien are back. Winston Reid is back in training today and is looking good. James Tomkins is close to coming back but James Collins is still ruled out through injury.”