I do not believe you can deliver oxygen or any gas mixture through a hose to 12,000’ depth.
Some better informed FReeper please correct me if that’s wrong.
Additionally there is nothing on the Titan to attach the hose to from what I understand. I don’t know anything about submarines or submersibles but I see only 2 ways these people are rescued. 1. If they are entangled in the wreck then maybe a ROV can disentangle them so they can surface. 2. They are already on the surface