The urge to make a “Maid in Manhattan” joke is definitely present, but she keeps it to herself for a better situation. One where her reason for visiting Maria isn’t as serious. So, the doorbell suffices.
She’s thankful, at least, for the courtesy. It’s probably helpful that she’s already home- less of an element of surprise if Natasha were to slip through a window ( or however she does it ). Two mugs go into the sink and she moves toward the door, checking the peephole first and barely suppressing a smirk when she swings it open.
“Romanoff. Come in?”