My daughter is about that height and she can't quite make it to a 700c frame yet. That of course will dependon the builder of the frame and the dimensions used. Here in Aus and my state NSW, a brand called Hillbrick is very thick on the ground amongst juniors. Our club is also really supportive of them as well and so has a variety of junior frames to choose from. At the start of the last season for us in Oct last year, she just made it onto the largest 650c frame. Perhaps next year she might make it to a 700, but she's a slow grower.
As for gearing, we are restricted. But having said that, my daughter still doesn't have the strength to push out her largest gearing. She's become pretty handy o a 42/16 and can really spin it out, but she will have to step it up if she really wants to progress.
Get your young one into it and encourage all the way. They are what truly makes our sport, and they are the basis for our next batch of potential olympians.