Best plus is +10 by Tom Bladon, of Philadelphia in 1977. He recorded four goals & four assists in the game. This might be the wildest anomaly to ever occur in the NHL. He's a D-man. He was known for having a big shot.
HOWEVER, he finished the season with just 35 points. So in the other 78 games he played, he got 27 points! I was well aware of the eight points/35 points, but not the +- record!
Doug Wilson, current GM of the San Jose Sharks, holds the dubious distinction of the lowest single game total. The total is not given on Wikipedia. I checked about 10 websites, but did not find out how dubious his record is. I'm a little surprised that the record isn't held by one of the 1974-75 Washington Capitals. My guess would be that the biggest minus would be similar to the biggest plus. In the range of -10.
SCOOP