Derrica's going to write a letter to the Chantry requesting information on her phylactery, namely if they are in possession of it she wants it returned to her. Basically the goal is 1. to get her phylactery back if it still exists/wasn't destroyed during the Annulment 2. to see if the Chantry intends on following through on old promises that she's heard of third hand.

What kind of response would she get?

Also, who is this letter addressed to? Does one write letters to the Divine??