Final answer:
The word that best fills the blank is 'swains'. It refers to the suitors or admirers of Rose who stopped pursuing her once they realized she was not interested in getting married.
Step-by-step explanation:
The word that best fills the blank is swains. In the context of the sentence, the phrase 'Rose was not in the matrimonial market at all' suggests that Rose was not interested in getting married.
The word 'swain' is a poetic term for a young man or suitor who is romantically interested in a woman.
So, in this case, the sentence means that once it became clear that Rose was not looking for a marriage partner, the admirers or suitors (swains) stopped pursuing her.