Now that you have identified that you need to have a conversation with your loved one, how do you actually sit down and have it? I suppose we should go back one step first though. Before you have this talk, be prepared to listen, be non-judgmental, be supportive, be prepared for the emotions everyone involved might experience and be prepared. If you can, do your homework in advance so you have some answers - know possible resources/options and costs. If you are pulling in other family members, ensure you are all going to be on the same page when you meet and not work at cross purposes.
The meeting location should be comfortable for everyone with limited distractions. If there is an agenda of sorts you can use it to stay on topic. Ensure you work in time for everyone to have a chance to talk and do your best to ensure that the person you are talking about has a chance to speak and is given every opportunity to stay in their own home for as long as possible, as long as it is safe, with supports in the home if necessary. Be careful not to argue, criticize or make it about the others in the room. The focus is and should only be the 'senior', why there are concerns, and solutions to fix them. Use observation and facts only. Don't demand or force anything. Focus on positive things and what can be done to help. Prioritize the things that are most important first and if you can devise a 'team plan' so responsibility is shared for the tasks required, things will be far easier for all involved. Set up a 'task list' for everyone. Keep in mind that this might be the first meeting of several and things may need to be monitored and tweaked as time passes. Sometimes if people see that all efforts have been made to keep the person in their own home, if relocation is ultimately required, it is far easier to accept and get 'buy in'.