What is required of one who left standing at Arafat before sunset due to his anxiety over his sick daughter, after having intended the obligatory Hajj?

The Hajj must be completed. Departing before nightfall necessitates a sacrifice (dam). Omitting the stay in Muzdalifah or Mina, or neglecting the stoning (rami), or the farewell circumambulation (tawaf (definition) al-wada'), necessitates a sacrifice for each missed ritual. Failure to perform the circumambulation of Hajj (tawaf al-Hajj) and its ritualistic running (sa'y) prevents the completion of Hajj and makes the wife forbidden to the man until he completes the Hajj with its circumambulation and running, and he must offer the obligatory sacrifices.