Final answer:
Bahadur Shah was the ruler of medieval Gujarat who surrendered Diu to the Portuguese.
Step-by-step explanation:
The ruler of medieval Gujarat who surrendered Diu to the Portuguese was Bahadur Shah. In 1509, the Portuguese decisively defeated a combined Egyptian-Gujarati-Calicut fleet in the port of Diu, one of the main ports of the Sultanate of Gujarat. Although the Portuguese did not take control of Diu, they received the right to establish a trading post there and a substantial payment in gold from the city's Muslim merchants.