Hi  Irushh,
Refer the below sample code. Here i have used Newtonsoft.Json library.
Use the DLL from below link and add reference to your project or website.
Newtonsoft Json
You need to import following namespaces.
C#
using Newtonsoft.Json.Linq;
using System.Web.Services;
VB.Net
Imports Newtonsoft.Json.Linq
Imports System.Web.Services
HTML
<div>
    <asp:TextBox ID="TextBox1" runat="server" />
</div>
<div>
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
    <script type="text/javascript" src="https://maps.googleapis.com/maps/api/js?libraries=places&sensor=false&key=AIzaSyCI2rrQ6FeYu6JvfehofKYLLKxkDxem78o"></script>
    <script type="text/javascript">
        google.maps.event.addDomListener(window, 'load', function () {
            var places = new google.maps.places.Autocomplete(document.getElementById('<%= TextBox1.ClientID %>'));
            google.maps.event.addListener(places, 'place_changed', function () {
                var place = places.getPlace();
                var latitude = place.geometry.location.lat();
                var longitude = place.geometry.location.lng();
                var weburl = "https://maps.googleapis.com/maps/api/timezone/json?location=" + latitude + "," + longitude + "×tamp=" + (Math.round((new Date().getTime()) / 1000)).toString() + "&sensor=false";
                $.ajax({
                    type: "POST",
                    url: "Default.aspx/GetTimeZoneName",
                    data: "{Url: '" + weburl + "'}",
                    contentType: "application/json; charset=utf-8",
                    dataType: "json",
                    success: function (r) {
                        alert(r.d);
                    }
                });
            });
        });      
    </script>
</div>
C#
[WebMethod]
public static string GetTimeZoneName(string Url)
{
    string timeZoneName = "";
    System.Net.WebClient client = new System.Net.WebClient();
    byte[] response = client.DownloadData(Url);
    string content = System.Text.Encoding.ASCII.GetString(response);
    JObject obj = JObject.Parse(content);
    try
    {
        timeZoneName = obj.SelectToken("timeZoneName").ToString();
        return timeZoneName;
    }
    catch (Exception ex)
    {
        timeZoneName = ex.Message;
    }
    return timeZoneName;
}
VB.Net
<WebMethod()> _
Public Shared Function GetTimeZoneName(Url As String) As String
    Dim timeZoneName As String = ""
    Dim client As New System.Net.WebClient()
    Dim response As Byte() = client.DownloadData(Url)
    Dim content As String = System.Text.Encoding.ASCII.GetString(response)
    Dim obj As JObject = JObject.Parse(content)
    Try
        timeZoneName = obj.SelectToken("timeZoneName").ToString()
        Return timeZoneName
    Catch ex As Exception
        timeZoneName = ex.Message
    End Try
    Return timeZoneName
End Function
ScreenShot
