Lord, to whom shall we go?
Simon Peter gives this remark in the form of a question to emphasize that he desires to follow only Jesus. AT: "Lord, we could never follow anyone but you!" (See: rc://en/ta/man/translate/figs-rquestion)
Here "his disciples" refers to the general group of people who followed Jesus.
This is an ellipsis for "the twelve disciples," a specific group of twelve men who followed Jesus for his entire ministry. AT: "the twelve disciples" (See: rc://en/ta/man/translate/figs-ellipsis)