You would talk to them as human beings. These are people who have made the decision to end their lives due to deteriorating health, a difficult decision that no one should have to make, but they have. You need to be direct and open with them but also compassionate and understanding. You would not be patronizing or dehumanizing. You would talk to them face to face and be as personal and friendly as possible. You could also choose to talk to them about their strengths and praise them for making such a brave and difficult decision.