What you have above is a crazy mix of different types of engines and networking libraries. I'm wondering if you know what you are shopping for?
RDS is a pretty decent, server-side engine, but it still only satifies a small section of all the technologies involved in an MMO. Never heard of MonsterSLS; I would steer away due to lack of community and resources. MINA and Boost.ASIO are purely IO engines that help with lower-level plumbing that you would have in a game server like RDS. Unless you think you want to roll your own (RYO) backend, they won't be of any use.
The problem is that an "MMO engine" is really a huge undertaking, because it ranges from lobby services, server management tools, advanced networking services, to umpteen other things. I can't think of a complete-enough one that is free.
The closest is BigWorld's indie license.