The colonel was arguing with a woman that if women are never brave and always get scared of every little thing. After this, the hostess was brave when a cobra was underneath the table.
The readers are the only ones that know that there is a Cobra under the table. Well, only the hostess and The American know that there is a Cobra. Apart from them, the readers only know that there is a Cobra under the table. None of the party guests know either.
The theme of the story is that gender has no impact on how you act. So technically, the woman and the colonel were both wrong. Neither one of their arguments were correct.