Who was the guardian of Lanka's gate that Hanuman defeated?

The guardian of Lanka’s gate whom Hanuman defeated was Lankini.

In the Ramayana, Lankini is the female personification and supernatural guardian of Lanka, Ravana’s island kingdom. Hanuman meets her while entering the fortified city in search of Sita, whom Ravana has abducted. She challenges the disguised or miniature Hanuman and demands to know why he is trying to enter.

Lankini attacks first, but Hanuman strikes her lightly and knocks her down. The encounter is important because Lankini recognizes that Hanuman’s victory fulfills a prophecy: a vanara defeating her would signal the beginning of Lanka’s downfall. She therefore accepts that Hanuman’s mission is divinely sanctioned and allows him to enter.

The other options belong to different stories. Tataka is a demoness defeated by Rama, Simhika is a sea demoness who attacks Hanuman during his journey to Lanka, and Surpanakha is Ravana’s sister whose humiliation helps set the larger conflict in motion. Lankini’s name itself means “woman of Lanka.”