Who do I need to notify when a loved one dies?

That depends on whether they were medically supervised, like on hospice care. If so, your first call would be to hospice so they can come and pronounce them dead. If it's an unexpected death, you need to call 911 and that will be a coroner's case. When I work with a family where someone knows they're dying, I usually assign a loved one to be the person who will call who needs to be called. Having assigned jobs at times of death is very important. Someone is getting food for the family who is starving, someone is making a list of who to call, someone does the calling and the email chains.