The father of the family ("the Big Man") kills Nag with a shotgun blast & Darzees' wife distracts Nagaina so Rikki can destroy her clutch of eggs.
Rikki-tikki fights 3 snakes, a Karait and two cobras Nag & Nagaina
Nag and Nagaina two King Cobras.
Rikki-tikki was fighting because he didnt want anything to happen to his newly found family
In "Rikki-Tikki-Tavi," Darzee is a tailorbird who serves as a source of information and warning for Rikki-Tikki. He is also portrayed as somewhat cowardly and fearful, relying on Rikki-Tikki for protection. Darzee's wife is killed by the cobras, which motivates Darzee to help Rikki-Tikki in his battle against them.
I think she did. It's been a long time since I read Rikki-tikki-tavi. Maybe as a mongoose , he already knew.
In the great war, Rikki-tikki fought Nag and Nagaina. Rikki-tikki fought the great war against the cobras who planned to kill the family in the big bungalow.
The denouement begins when Rikki-tikki gives Nagaina a "Hobson's choice" to choose either to satisfy her revenge or to save her last egg. She chooses to try and escape with the egg. Rikki-tikki pursues her into her underground lair & in the ensuing battle her kills her & destroys the last egg.
The big man in "Rikki-Tikki-Tavi" is the British family who takes in the mongoose named Rikki-Tikki-Tavi. They provide him with shelter and care while he helps protect them from the cobras that threaten their safety.
to live the mongoses alone and to save the garden
Rikki tikki is of course.
Rikki-tikki finds refuge in a bungalow and is rescued by Teddy and his family. Teddy's father helps Rikki-tikki recover and offers him a new home in their garden.
He sings a song of celebration after Nag's death & then a "death song" when Rikki-Tikki goes underground to fight Nagaina.