The whole last name concept, from A to Z, is goyish. Yidden, both him and her, traditionally never had a last name in the first place.
His name is Reuven ben Yaakov and her name is Dina bas Yaakov. You’ll never hear anyone being called up to the Torah by a last name. Even today. Similarly, since you asked about marriage, the kesuba will never have for him or for her (or for the eidem) any last name.