Williams deflected a shot from Haydn Fleury, making it 4-2 at 8:30 of the third period. He scored again to extend it to 5-2 at 15:02.
Geekie, selected by the Hurricanes in the third round (No. 67) in the 2017 NHL Draft, scored his second of the game on a wrist shot for the 6-2 final with 3:41 remaining.
Marleau gave the Penguins a 1-0 lead by driving to the net and scoring on a backhand at 9:19 of the first period. It ended his 17-game goal drought.
Geekie deflected a shot from Gardiner for his first NHL goal, tying the score 1-1 at 9:52 of the first. He took a flight at 8 p.m. ET Saturday after being recalled from Charlotte of the American Hockey League.
"I called my parents and my girlfriend right away. Said, 'Come on down. I got called up,'" Geekie said. "They kind of made it work. Fit it into their schedule. I'm glad they could be here tonight. … Just tried to go out there and keep things simple, adjust to the speed of the game and play hard out here."