She wants the bottom tier square, middle haxagon, top round. It doesn't sound like it's enough should she consider adding another tier?
Assuming each tier is 2-layer:
14" round serves 78
9" hexagon serves 26
6" round serves 12.
Total: 126. Not counting the 6" top tier, total servings = 114.
This is based on the wilton wedding chart, which is what I go by.