。
She regained her composure.
Literal
She [topic-は] composure [object-を] recovered.
落ち着きを取り戻す is a set expression meaning 'to regain composure.' 取り戻す (とりもどす, 'to recover, regain') is a compound verb combining 取る ('take') and 戻す ('return'). Useful vocabulary for emotional narratives.