Last week’s snowstorm put a halt to a monthly food distribution program that serves qualifying elderly throughout the area. This month’s distribution was about to be canceled, until Haverhill police and firefighters came to its aid. Run by Elder Services of the Merrimack Valley in conjunction with the Greater Boston Food Bank, the Elderly Brown Bag Program relies on a cadre of volunteers, who were scheduled to show up at Pentucket Lake School in Haverhill on March 5. But due to that Monday’s storm, the arrival of a truckload of food was delayed and this month’s distribution was in jeopardy of being canceled. Since the program’s regular volunteers were not able to show up this week, program organizers scrambled to find replacement volunteers.