Final answer:
The provided text does not contain information about what Malala's brothers were sad to see gone when they returned to Swat, and thus the question cannot be answered accurately with the given excerpt.
Step-by-step explanation:
The question refers to the book I Am Malala: The Girl Who Stood Up for Education and Was Shot by the Taliban, which tells the story of Malala Yousafzai's life and advocacy for girls' education. There isn't enough information in the provided text to accurately answer what Malala's brothers were sad to see gone when they returned to their home in Swat, as the details specifically regarding this are not included in the provided excerpt. Therefore, it would be inappropriate to speculate on the content not provided.