Looking at the picture and the exif. your shutter speed is to slow! Unless you were on a tripod, even then 50th of a sec is pretty slow to stop actions. That is one of the limitations of that lens. I owened one too, till I invested in the 70-200 is. f5.6 is as wide as that lens goes. The only way to get faster shutter speeds at that apeture would be bump iso up to 800, if not 1600. You will get more grain in picture, but you will be able to keep the shutter speed above 150 (I thnk) Faster the shutter speed, more you will be able to stop the motion.
Why the first girl is in focus, and not your daughter, looks like focus is on her, maybe they moved and you camera originnaly locked focus on the other girl. Or the other girl happed to stop her head at just the right moment while your daughter was still moving.