。
My father rarely comes home before eight.
Literal
Father [topic-は] 8-o'clock before [contrast-は] rarely returns-home not.
8時前にはめったに~ない stacks several elements: 前に (before), には (contrastive + location), and めったに~ない (rarely). The は adds contrast: 'before eight specifically, he rarely comes home' — implying he does come home after eight.