Theirs a Higher chance its Kenny, and there is a lot of evidence that show that the possibility is Kenny.
1. In Ben Survives Crawford situation, you see Kenny shoot Ben (Killing him) and Runs off, then complete silence from Kenny, even if Kenny was Killed (or Bitten) a sound from him would have been heard.
Plus the direction he ran, the Zombies would have been pretty close to Ben at that point when Kenny killed Ben, the zombies would have gone more for Ben, (but what about the zombies in the back?) well in that scene u hear a large "Drop" sound
it could mean that Kenny Pushed Some (or a) Zombie away from him and ran.
2. In Ben's Alley Death scene, Christa is looking seen looking into the Alley Kenny is nowhere to be seen (But Ben isn't seen either, But his Body could be Under that Huge Group of zombies at the bottom of the screen) and the Zombies in the back are very spaced apart Meaning that there was a possibility that Kenny Ran.
3. Same Scene, Lee Assumes that Kenny died, the assumption was probably right after he ran, and while the Zombies were crowding Ben (If u notice there are a lot of zombies when Christa is looking) Lee might not have actually seen Kenny die or run, and assumes the worst (Considering the conditions)
-Alternate Timeline-
1. In Ben's Death in Crawford timeline, Kenny goes down and helps Christa back up to the roof and he is stuck with all the zombies. and the sound of him "Dying could be heard" (well that's what i got from that scene anyway ._.) there is no sound, if he died zombies would pile onto his corpse and well eat him. (plus they say "where'd he go") Christa says "Maybe he ran away" when Lee was not taking the idea that Kenny was dead so good.
-Spoilers-
In the End after Clem either Kills Lee, or Leaves Lee to die, and After she saw her Zombified Parents, and after that small sequence at the end where she finds Christa and Omid, She must have noticed that Kenny wasn't around and Omid, and Christa most likely told Clem about Kenny's fate, Either way or told her, He might of "Ran away". Since she lost her "Child like Innocence" (its where she looks as if the world would get better, and everyone isn't "that" bad on the inside) she might have made the assumption that Kenny is dead since she never witnessed it herself to think of any other possibility.
Now for my Theory of Kenny's Fate, In the Aftermath of episode 1 Season 2 at the end, Alvin is trying to negotiate with a man "Hey put the Gun down man" and when the Camera looks through the "Bandits" none of them have they're guns raised, (Man) probably said something sounding familiar to Clem and that's why she moves to the front to see who it is, and Clem's possible assumption that Kenny's fate was wrong, shocked her a little. Kenny might have joined the "Bandits" after Savannah.
plus if it was Christa she wouldn't have gave that look at the end, it would have been with Relief that she isn't dead, not shock.
it couldn't be Lilly since she has trust issues with groups (Episode 2-3 season 1)
and No one from "400 Days" since Clem never met them (unless a Long disturbing flashback is involved to explain... which is doubted)
and its impossible for it to be Clem's Parents since they died in Savannah, (Evidence you ask? its in the phone message in Clem's house, Her dad was Bitten and you saw her mother in the ending of episode 5)
Vernon or the Cancer survivors? nope she never met anyone else accept Vernon, and Brie, Brie died, and Vernon is probably dead since he went to the ocean with the boat alone.
Lee? impossible, Same reason for Christa, Hershel cut off his leg not long after he was bitten, Lee didn't attend to it until his first blackout (that means the "Virus" has already reached a good portion of his body) Cutting it off at that point doesn't matter, unless they were to cut the "Whole" arm off there would have been the possibility he could have survived.
But its just a Theory... just had to throw it out there.