Facebook messenger integration - bot does not provide the responses

I had integrated the Dialogflow with Facebook messenger integration. I had followed the steps in the dialogflow docs.

I am not getting any output /message from the messenger.

I had used conv.ask() to respond to the Intents, is that the issue?

Do I need to update the surface capabilities section in actions?

'use strict';

  // Import the Dialogflow module and response creation dependencies
  // from the Actions on Google client library.
  const {
    dialogflow,
    BasicCard,

  } = require('actions-on-google');

  // Import the firebase-functions package for deployment.
  const functions = require('firebase-functions');

  // Instantiate the Dialogflow client.
  const app = dialogflow({debug: true});


  function getRandomInt(max) {
    return Math.floor(Math.random() * Math.floor(max));
  }

  const swamiMessages = require('./messages');

  const swamiQuotes =require('./quotes');
  // Intent Mapping 

  //INTENT: 'Default Welcome Intent'.

  app.intent('Default Welcome Intent', (conv) => {
    conv.ask(
        `<speak> <emphasis level="moderate" >   `+
        `Do you want to hear an Inspiring  <break/> Quote or a Message from Swami <break/> Sukhabodhananda ` +
        `Do you want to know about Prasanna Trust <break/>`+
        //`Do you want to know about the upcoming programs` +
      ` </emphasis> </speak>`);
    });

  //INTENT: 'quote'
  //Should get triggered when the user request for an inspiring thought
  // asks for motivation 

  app.intent('quote', (conv) => {
    // when the welcome intent is triggered recite a random quote

    //let quoteNumber= getRandomInt(5);
    //let quote = quotes[quoteNumber].quote; //
      let quote =swamiQuotes.getQuote();

    if (quote) {
        conv.ask(
            `<speak> <emphasis level="moderate" >   `+
            `Let us hear  an Inspiring quote \n` +
            `<break strength="strong"> </break>  `+
            `${quote}` +
            `<break strength="strong"> </break>  `+
            `\nDo you want to hear another quote or message ` +
            ` </emphasis> </speak>`);
        } else
        {
          conv.ask(
            `<speak> <emphasis level="moderate" >   `+
            `Let us hear  an Inspiring quote ` +
            `<break strength="strong"> </break>  `+
            `quotes` +
            `\nDo you want to hear another quote or message ` +
            ` </emphasis> </speak>`);
        }
  });

  // INTENT: message 
  //Should get triggered when the user request for an inspiring message


  app.intent('message', (conv) => {
    // when the welcome intent is triggered recite a random message
    let message =swamiMessages.getMessage();
    //let formattedMessage=swamiMessages.formattedMessage(message);

    conv.ask(
        `<speak> <emphasis level="moderate" >   `+
        `Let us hear  an Inspiring Message ` +
        `<break strength="strong"> </break>  `+
        `${message}`+
        `\nDo you want to hear another quote or message ` +
        ` </emphasis> </speak>`);

    });

Update

If I make changes to use the dialogflow-fulfillment library, how do I add two default handler functions - one for Actions on Google and one for other integrations? I'm doing something like

intentMap.set(null, googleAssistantOther);
intentMap.set(null, other);
//In place of null should i update the Intent Name and 
// googleAssitantOther and other are callback functions.