He returned again, offering to make her a lady-in-waiting, and then to dismiss the countess and marry her. The last offer would not have moved her even if she had wanted to be the countess, because the countess had helped her when her grandmother was ill.
The man returned, offering to make her a lady-in-waiting and then to dismiss the countess and marry her. This final proposal wouldn't have persuaded her even if she desired to be the countess because of the countess's past kindness towards her during her grandmother's illness.