Johnson scored 20 points in the first two quarters en route to finishing with 28 while Williams picked up the slack after halftime, pouring in 14 of his 16 after the break.
Hug began to get some first-half separation with a 9-0 run that started late in the first quarter. A layup by Reno's David Abittan tied the score at 8-8 with 2:29 showing on the first-half clock.
Hug then proceeded to score the next nine points in a span of 2:28 that bridged the first and second periods. An Andrew Johnson pull-up floater in the lane fell through the twine to cap the burst that left Hug with a 17-8 lead just over a minute into the second period.
Reno, the HDL's No. 3 seed, which upset Hug two weeks ago, was forced to play from behind the rest of the way and could never get over the hump.
"We just picked it up on the defensive end," Hug coach Charles Walker said. "I kind of shouted at them at that point to get going. We got some stops and our defense fuels our offense."
Reno did score six of the next eight points and got back to within five, 19-14 after a Hart McGrath bank shot at the 3:17 mark of the second quarter.
It looked like Hug would settle for a 25-18 halftime advantage after Abittan banked in a short jumper with 22 ticks left before halftime. That turned out not to be the case as Johnson buried a 3-pointer from the top of the key for the Hawks just before the buzzer sounded on the first half. The result was a 28-18 Hug lead at the intermission.
Reno just had no answer for Johnson, Hug's cat-quick point guard as he hung his 20 first-half points.
"We knew the challenges coming," Reno coach Kyle Schellin said. "We tried to make some adjustments in the second half, but we really we kind of figured, 'hey, they've already made all the jump shots they're going to make and if they keep making them it's not our night ... You have to give somewhere and we chose to give those guys pretty good looks. Guys stepped up and knocked them down. At that point, we knew it was going to be tough for us."
Unfortunately for Reno, the third period saw Williams get warmed up. He scored 10 of Hug's 14 points in the period.
After the Huskies scored the first bucket of the third, Hug proceeded to post 13 of the next 17 points. A 3-pointer by Hug's Jhalil Roscom capped the spurt that saw Hug forge ahead 41-24.
The 17-point gap was the widest margin of the night. Hug was still grasping a 17-point lead, 45-28 after a Roscom layup at the fourth quarter's 7:20 mark.
Reno responded with a last-gasp burst. The Huskies strung together a 9-0 run that came to a close after a Jake Johnson dunk. It helped Reno trim Hug's lead to eight, 45-37 with 5:07 to go in the contest.
"We were taking a lot of dumb shots at that point," Walker said. "We were jacking it up, but we stayed solid. We didn't get rattled. We stepped up and built the lead back up."
Hug stopped the bleeding by outscoring Reno 15-10 through the remainder of the postseason affair, accounting for the 13-point victory.
Johnson and Abittan each scored 14 points to pace Reno's offense.
Hug will meet Douglas at 6 p.m. today at Spanish Springs in the Northern 4A final.