You do not doubt it. The third Law of Newton really works. I would say it is the most reliable law of the Universe. Action and reaction. It is not subject to special conditions, it works always. If an object exerts a force over other object, the second object exerts a force of equal magnitude but in the opposed direction over the first.
So, the answer, undoubtedly, is that the ball exerts a force of 0.5 N over Alices's foot as she kicks it.
