Hoffman made it 2-1 at 9:36 with a wrist shot from the left circle on a 2-on-1.
Greiss made a sprawling pad save against Brett Connolly with about four minutes left in the third period to preserve the Islanders' lead. Anders Lee scored an empty-net goal with three seconds left for the 3-1 final.
The Islanders were 2-for-5 on the power play and 3-for-3 on the penalty kill.
"Every night, I see Greiss going, [Semyon Varlamov], it doesn't matter, we play in front of them," Eberle said of the Islanders goalies. "The whole [defense] are going and it seems we just roll on. So it's tough to really get too high and get too much of an ego. You have to put yourself and your egos aside and play within the structure and play the mentality that we have, and we've been winning hockey games doing it. We want to continue to do that. And when the special teams start to click on top of that, we'll be a tough team to beat."