Sentence 1: Loyd always wanted a treehouse. 
 Sentence 3: While up on the latter the dad slipped and fell 
 Sentence 4:  He broke his neck and died 
 Sentence 5:  Loyd has never fully recovered from his mother's constant blame 
 Option 1: His dad finally agreed to build him one. 
 Option 2: His mom finally agreed to build him one.