。
She takes pride in her son.
Literal
She [topic-は] her own son [object-を] pride [as-に] is-doing.
誇りにする ('to take X as one's pride') uses the productive [X]を[Y]にする pattern — 'treat X as Y / make X into Y' — and leans outward toward attitude and behavior. The closely related 誇りに思う ('regard with pride') is more inward and focused on subjective feeling. The two are often interchangeable, but にする has a slightly more behavioral or public flavor: she doesn't just feel proud, she carries herself with pride about him.