How to get Meteor.Call to return value for template?

From the Meteor.call documentation:

On the client, if you do not pass a callback and you are not inside a stub, call will return undefined, and you will have no way to get the return value of the method. That is because the client doesn't have fibers, so there is not actually any way it can block on the remote execution of a method.

So, you'll want to do it like this:

Meteor.call('abc', function(err, data) {
  if (err)
    console.log(err);

  Session.set('q', data);
});

Template.hello.greeting = function() {
  return Session.get('q').foo;
};

This will reactively update the template once the data is available.

This happens because Npm.require has Async behavior. That's the reason that you have to write a callback for Meteor.call.

But there is a solution, just use install(mrt add npm) and you'll get a function named Meteor.sync(//...) with this you can do both games: sync and async in your Meteor.call().

Reference: http://www.sitepoint.com/create-a-meteor-app-using-npm-module/