List<PointLatLng> _point;

 gMapControl1.ShowCenter = false;
 _point = new List<PointLatLng>();

 private void RiversMap_Load(object sender, EventArgs e)
    {
        gMapControl1.MapProvider = GMapProviders.GoogleMap;
        GMaps.Instance.Mode = AccessMode.ServerAndCache;
        GMapProviders.GoogleMap.ApiKey = @"abcdefghijklnop12344";
        _point.Add(new PointLatLng(headlatitude, headlongitude));
        _point.Add(new PointLatLng(headlatitude, headlongitude));
    }

private void Button2_Click(object sender, EventArgs e)
   {
        var route = GoogleMapProvider.Instance.GetRoute(_point[0],_point[1], false, false, 14);
        var r = new GMapRoute(route.Points, " My route");
        var routes = new GMapOverlay("routes");
        routes.Routes.Add(r);
        gMapControl1.Overlays.Add(routes);
        gMapControl1.UpdateRouteLocalPosition(r);


   }

routes was null