Housing Benefit

My adult son (who has autism) is having difficulty finding accommodation.  His tenancy with a private landlord has recently ended. We could just about manage to buy a flat for him to live in but only if we charged him rent to cover running costs.  As he is currently unemployed he would need to claim housing benefit but we are unsure (having read conflicting guidance) whether such a claim would be successful. Would welcome advice from anyone who has been down this road.