And what exactly gives the OP the right to make those decisions? The OP isn’t the friend’s next of kin or court appointed legal guardian. As far as I know, the OP is not a physician and is not qualified to give medical advice. Be supportive where you can, but recognize it’s for the patient, their family, and their medical team to decide on the appropriate medical care.
The OP has given us no reason to believe that her friend is mentally incompetent to make her own medical decisions. The OP may disagree with what her friend is doing, but a person making arguably suboptimal decisions is not an emergency justifying emergency guardianship.
First, very sorry for your friends news. Second, the thing I learned about cancer is pretty simple. You have to go to the best cancer center for YOUR type of cancer ASAP. You cannot stay in a local center, or go to a doctor someone recommends. There are many centers who with take you and will try to make you stay IF you have good insurance. This is especially true if you are in an area where many others do not have good healthcare. We lost a friend who was 30 years old. He moved to a specialized center too late. He didn’t die from cancer but from being too weak to handle the cure. Not all cancer centers are the same.
I would be very careful about what you suggest. Usually there is someone very close to the patient. That is the person who should be making decisions. One of the worst things you can do is try to suggest a plan. That’s the patient and doctor’s role. If there is someone who can help her (like her child you could reach out to them). Stop yourself from saying you looked it up on the internet or know someone who said XYZ.
I am absolutely not the decision maker and do not want to be.
I am simply putting together options for her, at her request.
She is still making her care decisions. This may not be the best idea given her sleep deprivation and high dosages of fentanyl patch and oxy, but it is what it is.
This is a difficult situation as she has no spouse, partner or siblings. Her mother is also fighting cancer right now. Closest relative is the cousin who has been taking her to appts, but seems very overwhelmed right now.
My designated role is research and options, and that is what I am doing.
Has anyone called her son? Does she have a good relationship with him?
I really feel for you, I’m sure you are overwhelmed trying to help your friend. 
Way to go Rockvillemom. They have asked for your help and you are helping. You aren’t overstepping IMHO.
People who have never been in the position of watching a loved one suffer and not being able to relieve the pain are very fortunate. People who have been in this position deserve our support.
@rockvillemom, you continue to have my sympathy and my admiration. You are giving much of yourself to your friend.
@rockvillemom - it sounds like things are advancing rapidly with your friend, but I wanted to make one more suggestion for your research. There are a lot of stage 4 melanoma blogs out there - many don’t have happy endings, but some are active and fighting, and most importantly, the authors are from different areas of the country (and global). Many of them mention their doctors and hospitals - perhaps you can find someone in your local area who recommends their care team. There are also forums to search but the blog idea seemed worth mentioning as my melanoma fighting friend actually met a stage 4 melanoma blogger who lived in our city and saw the same doctor and she found it helpful.
Continued best wishes to your friend. I am so sorry for the pain she is in.
She has an appt at the James M. Stockman Cancer Institute (a MD Anderson affiliated center) for a second opinion. That was my goal and I feel better now.
OP - I haven’t read through all the responses but wanted to offer my support and prayers. A second opinion is definitely warranted, even if it’s for peace of mind. I hope your friend is as comfortable as possible.
@rockvillemom who will be going with her to the second opinion? Someone with a clear mind needs to go along with her…with a notebook…and take notes. She should have questions before she goes…written down…so they aren’t forgotten.
She needs to ask about pain management, and perhaps get info about palliative care…as well as potential treatment options.
She no longer drives, her cousin will take her and take notes.
I think the question is - here is the current plan - Opdivo IV treatment every 2 weeks and waiting to see if that shrinks the tumors; fentanyl patch, oxy and Lyrica for pain - what would you do differently or do you concur with this plan? She has reacted poorly to the steroids so that has been drasticaly reduced - what alternatives might they suggest that would have the anti inflammatory benefits of steroids without making her manic and unable to sleep?
I’d keep some of it more simple.
- I am in terrible pain. What can be done to better manage the pain?
- What treatment options are there for me?
Steroids may counteract the benefit of Opdivo. I am sure her doctors know this.
She may also wish to ask if there is something she can take to help her sleep. She needs to sleep for optimal chance of healing and also pain relief.
@rockvillemom Your friend could definitely use resources to help her go through treatment–a cancer support center, which I mentioned upthread. I know you said you are in Maryland–I did a quick google search and saw this program:
https://hopeconnectionsforcancer.org/FAQ
It’s free and looks very similar to the cancer support organization where I volunteer. If you or someone could call for her and describe her treatment and explain her issues with pain, it’s likely that this center may have support groups for people with advanced cancer or services like oncology massage to help her as she goes through treatment.
Confused about comments on hospice–has she decided to stop treatment completely?
This has also probably been mentioned up stream but many hospice programs are willing to consult with patients and families on pain management issues even if they are still in active treatment and not ready for traditional hospice care. They truly are the experts on symptom management and pain relief.
Many hospice programs consult with families, if the patient is not yet ready to move in this direction.
Some hospice programs also have a palliative care program affiliation.
@Bromfield2 - thank you for the link. I think she is set as far as her plan for the next 2 weeks. Opdivo and new pain mgmt dr on Friday and then appt for second opinion at James M. Stockman Cancer Institute set for 1/14. I don’t want to overwhelm her with more ideas or suggestions right now. She seems to be sleeping better now that the steroid dosage has been reduced. I am hoping the new pain mgmt dr can help her as that remains a major issue.