The correct option is
C A vampire has a cross in his house.
There are three types of irony: verbal, situational, and dramatic. Situational irony occurs when the
actual result of a situation is totally different (often, completely opposite) from what you'd expect the result to be.
Option C is correct. The situation here is a vampire living in his home. One would not expect a vampire to keep a cross - something that vampires cannot tolerate - in their house. But, this vampire does. The situation is totally opposite to what we expected. Thus, it is situational irony.
Option A is incorrect. The situation here is a cat and dog in a setting. Cats and dogs are known to be enemies and the result of this situation is exactly what we expect - the car naturally runs away from the dog. There is no irony here.
Option B is incorrect as it describes a normal situation. There is no unexpected result in this setting. There is no irony.
Option D is incorrect for the same reason as B. It is just a mere statement. There is no surprising twist, and therefore, no irony.