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Your father's bankruptcy was a stain on the family name.
Literal
Father [genitive-の] bankruptcy [topic-は] family-name [genitive-の] stain was.
A melodramatic declaration with a metaphorical 汚れ ('stain, blemish, disgrace'). 家名の汚れ ('stain on the family name') is a fixed expression for something that brings dishonor to a family's reputation — the kind of phrase you'd encounter in historical drama, classical literature, or formal admonition. The 汚れ here is figurative, not physical dirt. The sentence is elliptical and bare-bones: just topic, predicate, and copula — but the formality of the vocabulary (家名, 汚れ as disgrace) signals a heavier emotional weight than the grammar alone suggests.