The DAV Mobile Service Office (MSO) will make a stop in Billerica at the Billerica Moose Lodge, 104 Boston Road, North Billerica, MA 01862 on September 23, 2015. DAV National Service Officers (NSO) will help you file a claim for benefits and stick with you all through the process in thanks for your service to our country. This is a free service of the DAV.