JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://cdn.rawgit.com/Eonasdan/bootstrap-datetimepicker/e8bddc60e73c1ec2475f827be36e1957af72e2ea/build/css/bootstrap-datetimepicker.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.1/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://momentjs.com/downloads/moment.min.js"></script>
<script src="https://getbootstrap.com/dist/js/bootstrap.min.js"></script>
<script src="https://cdn.rawgit.com/Eonasdan/bootstrap-datetimepicker/e8bddc60e73c1ec2475f827be36e1957af72e2ea/src/js/bootstrap-datetimepicker.js"></script>


<select id="FirstDDL">
    <option value="19/10/2017">RID19 </option>
    <option value="20/10/2017">RID20</option>
    <option value="21/10/2017">RID21</option>
    <option value="22/10/2017">RID22</option>
    <option value="23/10/2017">RID23</option>
</select>

<br/>
<br/>
<div class="clearfix"></div>
  <div class="row">
          <div class="col-md-6" style="position:relative">
<input size="16" type="text" value="" class="form_datetime">
</div>
      </div>

JavaScript

$(document).ready(function () {
        $('.form_datetime').datetimepicker({
            defaultDate: new Date()
        }).on('dp.change', function (ev) {
            var Newdate = ev.date.format('DD/MM/YYYY');//format it with moment.js to get output like 24/10/2017
         
            $("#FirstDDL option[value='" + Newdate.toString() + "']").attr('selected', 'selected');


            //send ajax call to .NET MVC controller if you need to get a complete new DDL
            //$.ajax({
            //    url: '/Home/GetData',
            //    data: { date: Newdate },
            //    success: function (data) {

            //    }

            //});
           
        });
    });