I worked in long term care for a number of years and it sounds like this facility may have a problem with communication. We did a lot of faxing to the doctors offices because we could never get in touch with these docs. However, we had a system in place so we knew whether or not we had gotten responses back from our faxes. Somebody dropped the ball here. Who was supposed to follow up on Sunday morning? There was a doctor somewhere on call. I would have kept calling the answering service and telling them it was an emergency until I got a live doctor on the phone.
The nurses who passed the meds on Sunday, Monday and Tuesday flubbed up big time. Someone should have left a big sticky note, paper clip or something else to get everyone's attention on that patient's medication sheet that her doctor needed to be called. Didn't anyone notice that the patient had no Coumadin in her medicine drawer? Where was the pharmacy, by the way, in all this?
It was state law where I worked that we had to contact the admitting doctor within 24 hours to verify his orders voice to voice or get his signature. If we could not reach him we had a "house doctor" who we could reach 24 hours a day to help us out with this kind of problem.
Your friend does not need to talk to a lawyer unless she is served with a lawsuit. Let the nursing home handle this. They have some explaining to do because it sounds like they did not have communication systems in place to deal with a situation like this and there is inadequate supervision. I think Casper1's previous reply is right on. I don't think your friend is going to lose her license.

But she should learn a good lesson from this. Question everything. Be particularly careful with new admissions in nursing homes. Goof ups on nursing home admission orders happen a lot more than you would think. If she can't get answers then pass the buck to the supervisor and put the ball in her court. When you are an Indian you are always safer when you pass the buck and let the Chiefs figure out what to do. Nursing homes are under a lot of scrutiny because of things like this happening. I still say that with this being a new patient there should have been a slue of people just pouring over this chart and assessing this patient in order to work up the care plan and prepare the MDS. Someone should have caught this.
Tell your friend not to alter this patient's medical record in any way or make any written statement indicating that she was negligent as that is as good as saying, "I'm guilty, I did it."