How to remove firearms from the home of my parents legally and ethically?

For context, my parents, 83 and 85, both have Alzheimer's, dementia, and memory loss. Their symptoms have increasingly worsened over the last decade. In addition, my father has anxiety, paranoia, and wanders. My mother has high levels of frustration and will hit herself in the head when she becomes agitated. They both have sundowning syndrome, which makes things worse. Their short-term memory is almost non-existent, but long-term memories remain fairly well intact. My father has also been found wandering the streets after midnight wearing nothing more than a Depends. They live in Illinois and have my older brother providing caregiving. (He has already procured legal paperwork (Without really discussing this with other family members) to get a General POA, Medical POA, Trustee, and Executor of the Will. (This is a separate issue I will most likely have to deal with at a later date.) My wife and I live in Virginia and have been unable to travel back to Illinois for 12 years. The issue is that my father has owned many firearms, some passed down from generation to generation. Among them, several shotguns, rifles, and handguns. There are easily more than 10 in total. They are locked in a gun safe in his bedroom with the ammunition. He supposedly retains the key as I have been told. I currently have 3 older brothers, all of whom have felony convictions, one of which may be ending his 30 year sentence in about 10 days to be potentially released. (Another issue I don't need to get into right now). I am retired military and a 100% disabled vet. I have no felony convictions or drug problems. My nephew, who was the primary caregiver for years, violated his felony probation and will be sentenced to prison later this month. No family members, besides myself, have a driver's license. This has led to many missed/cancelled/rescheduled doctor's appointments for my parents. (again, another story there). The only other close family member is a niece who lives not far from them. But she works as a nurse full time and has a family. She also recently within the past 18 months lost her father (my brother), and her father in law, and she has been dealing with that. I have brought this up to her as a concern many times over the past 6 months, and she agrees that the firearms should be removed. It's time to retire the guns and hunting. But has taken no action. I have talked to the police in town and they too agree that the weapons should be removed from the premises and secured. Another issue with this is control of family assets. My brother has stepped in and basically claimed everything as his, taking possession of vehicle titles, taking inventories, and going through every nook and cranny looking for valuables, jewelry, safe combinations, stocks, checks, loose cash, etc. (He too has mental health issues, paranoid delusions, schizophrenia, long-term drug abuse, alcohol abuse, inhalant abuse (huffing canned air), with moderate brain damage and inability to express clear thoughts through communication. He has convinced himself and my parents that others are stealing from them. (My father was also a hoarder and would "collect" anything. American Pickers Frank Fritz had literally been to their home.)So what should the best course of action be?I am not some gun nut. (Yes, I served 22 years in the military, 2 different branches, and have fired many weapons over the years as well as served as unit armorer and range NCO/safety for dozens if not hundreds of quals. But I have never actually owned a firearm. I am literally the most qualified in my family to even own firearms. (not to mention the only one who can legally own one, other than my niece, but I think she wants to keep guns out of her home and away from her young son). These firearms have little to no sentimental value to me, so I am not trying to jump on the inheritance early. I have simply kept distant and expressed no interest in being involved as the family has had their issues. Advice?