The audience first get a look of Alison's savior in "A DAngerous GAme" when her hand comes out of the ground similar to what happened in "This Is A Dark Ride". Alison's hand is seen poking out of the ground, attempting to get out. More of what happened during that flashback was revealed in the Season 3 finale, when someone pulls her out of the ground. Revealing that Alison did not die after being buried alive, but only the person's arm was shown.
While The Liars are in Ravenswood, Carla Grunwald approaches them and tells them that she went to go see Alison that night, after having a horrible premonition about her. She went in her backyard and saw Alison's hand poking from out of the ground, reaching for dear life. She pulled her out and said that Alison was confused, and her head was bleeding. Carla drove her to the hospital and left Alison in the car to get help. When she came back, Alison was gone.