A woman badly burned in a Monday house explosion has died from her injuries. Seventy-seven-year-old Mary Post was trying to ignite a pilot light on a gas heater that officials said had malfunctioned. She was taken to the burn unit at Arkansas Children`s Hospital, where she died yesterday. Her home was destroyed and neighboring homes were heavily damaged in the blast, which occurred in an area between the Arkansas Capitol and the state schools for the deaf and blind. Firefighters said Post had made several service calls on the heating unit over the weekend. Although they suspect the heater was to blame, authorities have not determined the direct cause of the blast.