Her Mom,

There are two issues. First, is she physically ready? If she has been swimming for a competitive swim club for 3x+ a week for two years, she is likely physically ready for the swim. It is likely that she could be swimming 2 miles+ each practice. The next issue is the psychological issue. Is she concerned by the open water ? Open water swims are very different  from pools, but very fun and exciting. She should have a blast. The start is very different...no lane lines, and everyone bumping into each other. Tell her to expect that and it's ok. Next, she'll have to get used to picking her head up every 10-15 strikes to make sure she's headed in the right direction...an annoyance , but not a problem. Finally regarding pre race food. I would recommend the normal hydration, principally water maybe some gatorade sort of drink, and maybe a banna. But, not too much.  Just encourage her to look forward to the experience, and to enjoy all the fun.

Open Water Masters Swimmer