An exception to a generalisation is applied to cases where the generalisation should apply.
This is clearly fallacious since exceptions should be applied with care.
Because we allow terminally ill patients to use heroin, we should allow everyone to use heroin.
Because you allowed Jill, who was hit by a truck, to hand in her assignment late, you should allow the entire class to hand in their assignments late.
Identify the generalisation in question and show how the special case was an exception to the generalisation.