Elena isn't the biggest fan of Vanitas after their very brief interaction, but if she somehow picks up on his reluctance to go down to the market being because of a fear of the water, she'd sympathize pretty hard and try to help somehow. Her parents drowned in a lake, she drowned in a lake, lots of sympathy for fear of water. She's pretty perceptive about things when people are putting up a front, so if you're interested in seeing how things go... She might even offer to go shop for him so he doesn't miss out entirely.