Nicky Kohen has every reason to hate Hanukkah. Her father, Josef Neumann, was slain by a madman during the Festival of Lights three years ago in upstate Monsey — fatally stabbed during a holiday party. But in the years since, the births of her son and a nephew have helped Kohen and her family find “light in all the darkness.” “As Jews, we don’t give that up just because something bad happened,” Kohen, 31, told The Post, at times choking up. “There’s family celebrations. We light the menorah with our children every day.” “We get together, we celebrate both Hanukkah...