Williams had 210 yards passing for the Hawks (2-3). He also rushed for 70 yards, including a 22-yard dash for a touchdown to cap the game's first possession.
Williams' 50-yard scoring pass to Reggie White, Jr. with 1:16 to play broke a 24-24 tie and gave Monmouth the victory.
White caught another touchdown from Williams early in the first quarter on the team's second possession. The Bulldogs (2-2) scored twice in the second quarter to even it up 14-14 at halftime.
Easton threw for 256 yards and two touchdowns for the Bulldogs.