。
She walked hunched over like an old woman.
Literal
She [topic-は] old-woman [like-のように] head [object-を] lowering walked.
~のように marks a simile — 'like an old woman.' 頭を下げて literally means 'lowering one's head,' here describing a hunched posture rather than a polite bow. 老婆 (ろうば) is an unvarnished word for 'old woman' — less polite than 老婦人. The te-form 下げて provides the manner of walking.