Final answer:
Luke's lightsaber was concealed inside R2-D2 and was ejected to him at the right moment during the scene on Jabba's sail barge in 'Return of the Jedi'.
Step-by-step explanation:
The character in Jabba's palace who had Luke's lightsaber in Star Wars: Episode VI - Return of the Jedi was not explicitly among the options provided (A. Bib Fortuna, B. Salacious B. Crumb, C. Gamorrean Guard, or D. Rancor). Luke's lightsaber was actually concealed inside R2-D2, who was serving drinks on Jabba's sail barge. At the right moment, R2-D2 ejected the lightsaber to Luke Skywalker, who caught it and used it to fight against Jabba's guards.