A lullaby is a song sung to soothe babies, so her singing to him like a lullaby would indicate that she was singing to him calmly and peacefully.
Context: "She would sing to him calmly when they were young, while she was alone on horseback by the creek."
Hypothesis: By the creek, alone on horseback, when they were young, she would sing him like a lullaby-soothed baby .
Based on the context, is the hypothesis true, false, or unknown?