Speak with Stephanos to purchase a hippogryph ride back to Blood Watch. Once you have arrived, deliver Nurguni's Supplies to Caregiver Topher Loaal.
If I remember correctly, Blood Watch's hippogryph master is Laando. If you've spoken to him before, then you can take one of my hippogryphs to him.
That's a good lesson to know: hippogryphs are always trained to fly to their capital city, but they'll only take you to a remote hippogryph master after you've already been there.
Since you arrived on one of Laando's hippogryphs, you can also use that route to return to Blood Watch with the caregiver's supplies.