I don't think there is a single correct answer.
I think the answer they want is "If I saw her tomorrow I would speak to her"
Alternatively, I'd say "if I were to see her tomorrow I'd [or "I would"] speak to her". That option isn't available but I think sounds better.
However, I think most people would simply say "If I see her tomorrow I'll speak to her" and everyone would understand what that means, so it seems 'correct' to me. It's probably what I'd say- anything else sounds a bit highfalutin.