I fail to see how dropping the earrings on the floor is anything but fumble fingers, which last I checked was not a criminal offense. If the clerk is saying that your daughter was trying to drop the earrings into a purse and missed and they went on the floor, or took the earrings out of a purse and dropped them on the floor to avoid having them on her, then there is a problem, as it is likely that there was a surveillance camera filming what was going on, although the angle(s) of the camera(s) taking the shot(s) may not have picked up anything.
Your daughter did the correct thing in not saying anything until you arrived. The next step is to hire an criminal defense attorney to represent her. A theft conviction carries a terrible stigma forever when she will be applying for schools, jobs, credit, etc. The attorney can investigate to see if there is video, and if so what it shows and does npot show, and question the store/state witnesses. If the evidence is strong, the attorney can try to get your daughter into a pretrial diversion program which if successfully completed would lead to the charges being dismissed, or at least agree to a withhold of adjudication so that her record may be sealed later. If the evidence is weak, the attorney can work on the prosecutor to drop the charges now. Either way, your daughter needs an attorney to protect her interests.
Without having more facts or witness statements to review, it is difficult to be too specific, but I hope this information is helpful. Please click Accept so that I may be credited for my assistance. Thank you and good luck.