"My Favorite Mother-In-Law" is a memoir by Mark Niemann-Ross, exploring his insider experience as the youngest resident of Greta's assisted living facility. Mark and Greta share a unique bond, and the book explores themes of aging and family dynamics. The narrative fills the book with humorous anecdotes, touching memories, and insights into Greta's life, including her upbringing, religious views, and her role as a nurturing figure in the family. In addition, Mark's memoir showcases his deep respect and affection for Greta, as he considers her his mentor in aging gracefully. The book captures the essence of family love, acceptance, and the enduring impact of a beloved mother-in-law.