The issues here are two.
First, is morphine the correct drug for this patient? Morphine is contraindicated in patients with renal impairment, in most cases. The metabolites can indeed cause serious neurological toxicity. If the patient MIGHT have renal impairment, but death is near, then there probably isn't any reason to stop the morphine, and no reason to advise caregivers to reduce the amount of morphine being given. Remember, as an RN you can't make up orders, the range specified by the physician must be followed unless it is changed by the physician. This is certainly the case in an actively dying patient. Concerns about neurotoxicity in the last hours of life are probably unwarranted. Comfort is paramount in this instance, and why change something that "isn't broken"? If your patient is not actively dying, and renal impairment has been established, then advocate for a different opiate. Better choices would be oxycodone (although liquid oxycodone is outrageously expensive), or even methadone (if the patient can tolerate pills). A fentanyl patch could be considered in some cases.
Second, in hospice, we don't pay a lot of attention to the "textbooks" concerning appropriate use of medications. We use medications for a very different purpose. Comfort is the key to everything. We measure all outcomes based on this golden ideal: If the patient's comfort level is better because of the medication, we have succeeded. Therefore, if your patient is comfortable and not showing any signs of toxicity, to advise someone to give LESS of the medication . . . well that's counter-productive to our goals. By the way, we don't really "push" morphine and lorazepam (at least good hospices don't), but we do focus on the symptoms and relieving those symptoms using the medication arsenal that's made available to us.
It takes a while to get use to hospice principles when you first enter hospice. You will find that hospice nursing is very different from acute care nursing, but it is also extremely rewarding. Just don't worry quite as much whether you are going to kill your patient or not. You won't. The disease will.