The Catamounts (12-6, 5-1) have a half-game edge over Albany and the Seawolves (13-5, 4-1), whom they defeated in last season's conference tournament final.
Rusin scored eight points during a 12-0 run early in the second half that gave Vermont a 44-29 advantage.
Stony Brook, after trailing by as many as 18 points, got to within four, 65-61 with 2:48 left, after a dunk by Tommy Brenton. But Sandro Carissimo responded with a layup and two free throws on Vermont's next two possessions for an eight-point lead.
Brian Voelkel had six assists for Vermont, giving him 405 for his career.
ESPN's Dan Dakich joins The Paul Finebaum Show to discuss the SEC's presence in the NBA Draft.
Ted Kapita was the top-rated recruit from West Virginia in the class of 2015 and recently played at DME Academy in Florida.
With the Suns drafting Tyler Ulis, they now have five guards on their roster who attended Kentucky.