Answer: Bilbo completes the transition from grocer to hero during his encounter with the spiders in Mirkwood Forest. Using the skills and courage he developed throughout the journey, he rescues the dwarves from the spiders, marking a pivotal moment in his transformation.
Explanation: During the encounter with the spiders in Mirkwood Forest, Bilbo initially struggles but then uses the Elven blade he acquired to fight and outsmart the spiders. This showcases his growth in courage and resourcefulness. Bilbo's actions not only save the dwarves but also prove his worth as a capable and heroic member of the group, earning the respect of the dwarves and completing his transition from an unlikely adventurer to a true hero in their eyes.
