What is our Moral responsibility to our neighbors, and cousins? The answer to that is the answer to your question.
Am I my brother's keeper?
A related question making the tours these days is to define and codify our social responsibilities, not only in coming on accident victims, but in the environment, and in economic aid, as well as individual assistance.
You could argue that an economic community's social responsibilities are driven to a great extent by its own imperatives - and all three of the available choices presented in the question potentially impact upon these to a greater or lesser degree. You might for example argue that...
(a) We don't promote democracy anywhere unless we perceive that it is in our own interests that we should. If we do, then one possible reason is that democratic neighbours are less likely to present a future threat to us than undemocratic ones, regardless of their internal politics.
(b) Why would we work to grow the economies of less-developed countries unless it serves our own interests to do so? If we do actively seek to grow a neighbour's economy, one possible reason might be that a more highly-developed economy in a neighbouring country is more likely to be able to serve our interests as a trading partner than one that is bordering on collapse.
(c) We don't care for the environment for its own sake, because if we did we'd never squander our existing natural resources to anything like the extent to which we actually do. Utilisation of natural resources is driven by our existing desires, needs and requirements: we only stop / slow down if it becomes apparent that we're damaging our own long-term interests if we don't.
If the above holds water (and you may well feel that the above rationalisations are unduly cynical) the question requires you to attempt to prioritize such considerations by the EU when formulating both its domestic and its foreign policy. What is more important: the economic advancement of the EC or security within the EC? Short-term or long term? Within the existing Community, or within an expanded Community? Just a few thoughts to play with!