Standing flatfooted seemingly just waiting for the season to end less than a week ago, the Rangers suddenly were picked up on a huge wave of emotion, one with origins in deep sadness, and one that is now carrying them to a decisive showdown. Following Sunday night’s 3-1 win over the Penguins at the Garden in Game 6 of this second-round playoff series, the Blueshirts have now skirted elimination two games in a row, and will set out for Pittsburgh for Tuesday night’s Game 7. And with them will be Martin St. Louis, the veteran winger who is still mourning the death of his mother, France, who passed away at the age of 63 on Thursday, and has lit a spark underneath this team that has saved their season. “I know,” St. Louis said on this most special Mother’s Day, “she’s helping me through this.” With his father, Normand, and his sister, Isabelle, up in the din of the suddenly awakened crowd on 7th Avenue, St. Louis drew all-important first blood for the Rangers just 3:34 in with a goal off his leg, his first point of the series, and one that brought down cheers of “Marty, Marty” so loud they shook the overhanging bridges. “When Marty scored that goal it was such a beautiful moment,” said goalie Henrik Lundqvist, who was as fiery and vocal during this game as he has been in some time, the only shot of the Penguins’ 37 that got by him being a Brandon Sutter floater that went off the leg of disheveled defenseman Kevin Klein late in the first period. “It got really emotional to watch that, and see him and what he’s been through,” Lundqvist said. “I think the entire team was feeding on that moment, and the entire building, it was such a great energy in here. “It’s up to us to give them something to be happy about.” The whole team was emotional, and much to the delight of the 18,006 inside, they played like a group possessed. From the opening draw, they were physical, fast, and pushed the Penguins around in all the difficult areas of the ice. They played stout defense, got under the skin of superstar Sidney Crosby, and walked away not only with their heads up, but seemingly shoving the Penguins’ face in the fact that they were the ones who have blown consecutive chances to move on to the conference finals.