someModelFile.js

module.exports = {
  "someMethod": ...
};

someRoutingfile.js

module.exports = function(app, model) {

  // attach routes here
  app.get("route", function(req, res) {
    model.someMethod(function(data) {
      res.render("thing", data);
    });
  });

});

someSocketIOFile.js

module.exports = function (io, model) {

  var channel = io.of(url);

  io.on("foobar", function(socket) {
    model.someMethod(function(data) {
      socket.emit("data", data);
    });
  });

});