Answer: el Canal de Panamá y las playas
Explanation: The question is " Which thing is going to visit the family in Panama?"
The third sentence; "También visitaremos el Canal de Panamá y las playas."
Says "We also will visit the Canal de Panamá and the beaches"
So the things that the family will visit are the Canal de Panamá and the beaches, or in Spanish:
Las cosas que van a visitar son el Canal de Panamá y las playas.