If the Royces had done something untoward and immoral, yes, but if they had simply become less wealthy, why would they take away the name? Then, to play devil's advocate, it could be only Jill's father who has financial problems, and the rest of the family could still be doing well.
However, I don't think that's the case, because otherwise Tybalt wouldn't be begging for his place at the Royce table, and Jill would have demonstrated her stupidity in humiliating him so terribly if she had a clay-footed giant behind her.