Answer:
The mistake committed by Darzee's wife in the story was jumping in front of Nagina and feign an injury on the wings. This task was meant to be done by Darzee, but he was too feather-brained to do this.
The consequence of this mistake was Rikki-Tikki-Tavi was able to give a tough fight to Nagina and defeat her.
Explanation:
Rikki-Tikki-Tavi is a short story written by Rudyard Kipling. The story is about a young mongoose, who combats with Nag and his wife, Nagina and defeat them successfully.
In the story, when Rikki-Tikki-Tavi asks Darzee for help, Darzee, being too feather-brained hesitate to do it. Darzee's wife knew that Nag's eggs would mean more snakes in the garden, so she quickly flung herself before Nagina feigning her injury on the wings. Though it was a mistake by Darzee's wife but it helped Rikki-Tikki-Tavi to defeat the snake family.
The result of this mistake was that Rikki-Tikki-Tavi was able to destroy Nagina's egg and present a choice before her either to choose her baby or hurt Teddy.
This move helped Rikki-Tikki-Tavi to kill Nagina and her family.
