Was Rikki-Tikki-Tavi justified in killing Nagaina?

Rikki-Tikki-Tavi was justified in killing Nagaina as she posed a direct threat to the safety of his human family and the other creatures in their garden. Her intent to kill the humans and her aggressive behavior made her a danger that needed to be neutralized. In the context of the story, Rikki's actions were driven by a protective instinct, aligning with the natural order of predator and prey. Thus, his decision to confront and eliminate Nagaina can be viewed as a necessary act of self-defense and guardianship.