She has been in and out of rehab for a year and a half, she is now refusing to get help and just lays in bed drunk all day. He is fed up and is done and is at a loss as where to go or where to take her.
If he has a problem with his common law wife, he needs to file for divorce. Common law marriage is simply a way of getting married. If a common law marriage has actually been established (you can read my guide on the topic for more information) then your brother is legally married and he cannot just toss his wife out of the marital home. He needs to file for divorce and sort out possession of the residence in court.
Your brother may choose to file for a divorce, and ask the Court to make orders regarding who has use of the residence. This is not a fast process. If your brother believes she is a danger to herself, due to her drinking, he may contact the police, and if they feel she is a danger to herself they may place her on a 72 hour mental health hold. She will be taken to a local hospital where they will sober her up, and then a determination will be made as to whether or not she needs to be held for the entire 72 hours.
Your brother may want to speak to someone to determine whether he is truly married, as not being married may open other options to him.