Hazrat Sauda (RA), wife of Prophet (PBUH), died during the caliphate of:

Hazrat Sauda bint Zam'ah (RA) was one of the wives of Prophet Muhammad (PBUH) and a revered figure in Islamic history. Her passing occurred during a specific period of early Islamic caliphate.

• Hazrat Umar (RA) is the correct answer. Hazrat Sauda (RA) passed away in the 23rd year of Hijra, which falls within the caliphate of Hazrat Umar ibn al-Khattab (RA).
• Hazrat Abu Bakr (RA) is incorrect as her death occurred after his caliphate.
• Hazrat Usman (RA) and Hazrat Ali (RA) are incorrect as their caliphates followed that of Hazrat Umar (RA).

This question tests knowledge of the timeline of early Islamic history and the lives of the Prophet's companions.