The lights were dim and the mood was somber Tuesday night during a memorial service held at Chabad of Dallas on Tuesday night to honor Rabbi Gavriel and Rivkah Holtzberg and others who died during the attacks in Mumbai last week. In his moving remarks, Rabbi Mendel Dubrawsky, who pioneered the Chabad movement in Dallas some 25 years ago, said that the Holtzbergs were the epitome of shluchim and shluchot (emissaries). They left the comforts of home, in Crown Heights and Israel, to be of service to Jews abroad. It was not a comfortable post, but they accepted their charge with vigor and grace. “They were lamplighters,” he said.