1st option is correct. 

Nasir-ud-din Mehmud was the last ruler of Tughlaq Dynasty of the Delhi Sultanate.

Nasir ud din Mahmud, Nasir ud din Firuz Shah (reigned: 1246–1266) was the eighth sultan of the Mamluk Sultanate (Slave dynasty). He was the son of Nasiruddin Mahmud (died 1229), who was the eldest son of Shams ud din Iltutmish (1211–36) and was said to succeed his father but died suddenly; however, he did become the governor of Bengal. He was named after his father, by Shams ud din Iltutmish, for he had grown an intense filial attachment, to the only begot son of his posthumous child.