Mrs. Wynnes, how did you know the cobra was under the table?
There's a cobra under the table. Place milk at the veranda.
The readers and other characters did not expect the cobra under the table to be crawling across Mrs. Wynnes's foot.
While the assumption, women being more frightful then men, was believed to be true, Mrs. Wynnes had perfect control under a terrifying situation, and others did not. This shows situational irony.
The above picture shows the theme, your gender has no impact on how courageous you are. Mrs. Wynnes was calm and courageous during this terrifying situation which shows that gender has no impact on someone's nerves which is a lesson that the characters learned.