She came running toward me, her hair streaming in the wind.
Literal
She [topic-は] wind [in-に] hair [object-を] streaming, my-direction [toward-へ] came-running.
髪をなびかせて ('with hair streaming') uses the causative of なびく ('to flutter/stream') in te-form as an adverbial — her hair fluttering is the manner of her approach. A vivid, narrative image.