As a former Hospice Nurse, I have seen INCREDIBLE amounts of medication given simultaneously without the patient ever skipping a breath. I once gave 4 mg. of the drug called Dilaudid every hour with a benzodiazepine such as Ativan or (Valium) and he never missed a beat. In fact, he moaned the entire time even though he was not really conscious. The terminally ill sometimes require massive amounts of a combination of drugs to control pain that would otherwise kill a normal human. The question you should ask is, does it control the pain? The object of hospice, which I hope is helping to administer and monitor these drugs, is to keep the patient functional as possible, without pain and to not die alone. With those kinds of medications, I doubt they are hardly functional. It sounds like with the combo you describe, the patient is way past meds that can keep them functional at this point. Don't worry about addiction or the long term effects at this point. Let this poor soul live out whatever days/weeks they have left pain-free and at some point, if they survive, don't be surprised about tolerance and an increase may become necessary to totally control the pain...if that is possible with some.
I went through this with my Dad and God love him, I would have given him any combination of meds to take away his pain. Be their advocate! Do what you can to make sure the doses are 1. Being monitored and 2. Are sufficient to control the pain with this terminal illness and always let them know you are there and for heaven's sake, don't let this person die alone. That, perhaps, is the most painful and cruelest of all.
Good Luck!