>>57889552
The second one. In the first option, the fact humans no longer exist is kind of negated by the fact (You) the reader exist to acknowledge May's suffering, and there's just nowhere to go from there. The second one seems more tragic because not only do humans exist, they don't know May is down there, so they'll probably go back to polluting the ocean with sewage and oil spills for her to enjoy. Which might actually twist her soul and make her hate humanity for abandoning her, opening up the tragedy to becoming a potential future revenge quest if you want to go there. Alternatively, maybe someone eventually does find evidence of May having existed or surviving, not long before May herself somehow starts making herself known to civilization again.