In general, all solutions except for B work. B requires specific hand placement on the device (size of the handset was not considered) to reach the buttons comfortably. C, F, and G don't deliver enough context because of the lack of text; you're right, the notion of a room versus a conversation needs to be expressed in text because the icons do not express the action directly.
A's icons are too small, and E is ugly because the text doesn't line up within the button and the buttons are huge (which will also pose an issue with different screen resolutions). H is also very iOS-style. I recommend D or G; I also recommend removing the cancel function entirely as a standalone button and allow the user to cancel by hitting the physical back button or anywhere else on the screen that isn't the two create functions.
Finally, I'd ask can a conversation be made without a room present? Because if so then you have a data problem where in theory a user can create a conversation without a room. Further, if there can be one without the other, how are they differentiated? These seem like much more challenging issues to tackle in your designs (though if you've already gotten past those, congrats!)