The owner of McKenna’s Pub on West 14th Street says that when 22-year-old Emily Singleton of Brooklyn left his bar at midnight on Saturday, she was with friends and "not drunk or stumbling or anything.” Allison Keller, 28, tells the Post that when she saw her about an hour and half later she was alone and disoriented in the 14th Street subway station, and had spilled her purse on the floor. Keller helped her get on the train and urged her not to get off when she saw her wobbling in the car, but Singleton bolted at Canal Street. She was found dead on the tracks there the next day. “I tried to help her, and then when she ran ... I just wanted to think it wasn’t her when they told me,’’ said Keller.