Hi and Welcome.
Your son is 26. He is choosing to have no place to go because he is choosing to feed his addiction. He's had numerous chances to get in recovery but he isn't ready yet. He has to do it in his own time. Not yours and not his brothers.
You are allowed to have boundaries. It's your house. And I see nothing wrong with having a boundary that states I will not allow drug users to live under my roof or support adults that should be working and supporting themselves. If you let an active drug user live in your house it enables him and supports his addiction. It will give him a safe comfortable place to free-load and use drugs. You would be protecting him from feeling the full negative consequences of drug use. And negative consequences are what eventually leads an addict to recovery.
If your other son doesn't understand this, suggest he read Co-Dependent No More or attend Naranon/Alanon with you.
Work the recovery you wish your son would work. Be a shining example of strength and recovery for him.
Went to alanon meeting tonight, just wish I knew what to do?
If you don't know what to do, do nothing for the moment and the solution will be revealed in time.