When an armed robber barged into a North Side motel room Wednesday night and ordered the six people there to the floor, he put a 70-year-old woman closer to her handgun. The great-grandmother knelt between the beds, reached into her purse on the floor and pulled out her .357 Magnum pistol. She fired one shot at the robber, who staggered from the room, collapsed in the parking lot and died. "It's a wonder she didn't shoot us all," said her 51-year-old son, who was preparing to hand over his cash when he heard the gunshot. "She's the worst shot in...