The win snaps a 10-game losing streak for SU (4-12, 1-7 ODAC) and comes in the team's league finale.
SU lost four overtime games during the streak, including three in ODAC play.
VanHorn had what proved to the game-winner, scoring unassisted in the 16th minute.
Hannah Johnson then set up Cross in the 48th before DeLuca tallied in the 63th and 67th minutes to provide the final margin of victory.
Goalkeeper Sarah Clare had to make just one save in the shutout.
SU outshot the Vixens 21-4 and held a 13-12 advantage in penalty corners.
Shenandoah completes its season on Tuesday with a non-league match against St. Mary's (Md.).