。
She was so hungry she ate anything.
Literal
She [topic-は] empty-stomached was [because-ので], anything ate.
空腹 (くうふく) is a more formal/literary word for hunger than 腹が減った or お腹が空いた — typical of written prose. The free-choice pronoun 何でも ('anything, anything at all') uses でも after the question word 何, paralleling 誰でも ('anyone'), いつでも ('anytime'), どこでも ('anywhere'). Used with positive verbs it means 'any X (at all),' with the implication of indiscriminate breadth — here, the sweep of hunger overriding any choosiness.