What is the name of the book that Twilly sent to Nick?

The book that Twilly sent to Nick is "HayDuke Lives." This novel, written by Edward Abbey, is a sequel to "The Monkey Wrench Gang" and continues with themes of environmentalism and activism. In the context of the story, sending this book could symbolize Twilly’s ideals and passion for the cause of environmental protection, which are central themes in Abbey's works. The book reflects a rebellious spirit and aligns with Twilly's character, showcasing his commitment to fighting against ecological destruction.

Other choices like "Earth Abides," "Into the Wild," and "The Road" focus on survival, nature, and dystopian themes, but they do not carry the same direct connection to Twilly's character or the act of sending a message related to environmental activism as "HayDuke Lives" does.