An easy-to-eat snack. A water bottle. And flip flops or some other shoes that are easy to slip on if she needs to run to the bathroom. It's unlikely she will need hair ties as you will have all that stuff ready to use in case of hair emergencies in your OWN mama meet bag (which should include hair elastics, an extra scrunchy in your team's required color, bobby pins, snap clips for stray locks of hair, a comb and a brush, and got2bglued hair gel AND hairspray, for the gym mom who does NOT fool around
) She will need to be able to put her warm up jacket and leggings in the meet bag, but she may also need some socks if her feet get cold between rotations. Some of DD's teammates have stress-relief/relaxation essential oil blends to sniff also if they become nervous between rotations. My DD has done fine without that.