The statement that is false is the following: the castaways tells Pi about his wife and family.
Pi speaks to the French castaway, who is a blind man, when he becomes temporary blind from a delirium caused his deteriorating condition. The castaways speaks to him of food, beef and brains and all sorts of food, which Pi does not like. They also speak about murder, Pi asks him if he ever murdered someone and the man answers that he had killed a man and a woman. When they join their boats, the castaway tries to kill and eat Pi, but Richard Parker kills him before he can accomplish this.
The castaway never speaks to Pi about his wife and family, and therefore, that is the false statement.