Ryan Gesiakowski scored 10 points and DeMuynck finished with a game-high nine boards to help the Panthers (10-14, 5-6) outrebound Grambling State 41-37 and outscore them in the paint 26-20.
Ahead 28-22 at halftime, Prairie View A&M opened the second half on a 12-2 run to go up 40-24 with just over 14 minutes remaining.
Montgomery led Prairie View A&M with 13 points, as the Panthers shot 50 percent (13 of 26) in the second half. Prairie View A&M led the entire game.
Grambling State shot 35.7 percent (20 of 56) for the game and trailed by as many as 17 points.