Until a js guru drops by my observations may help a little. 
I notice that in this js file.
<script type='text/javascript' src='https://test.trazdd.site/wp-content/themes/betheme/js/scripts.js?ver=17.8.6' id='jquery-scripts-js' defer></script>
There is an undefined error for the variable called rightW
.
var rightW = $('.top_bar_right').innerWidth();
There doesn’t seem to be a top_bar_right element and so returns undefined and the width never gets set on top_bar_left.
var leftW = parentW - rightW;
$('.top_bar_left, .menu > li > ul.mfn-megamenu').css('width', leftW);
It’s that lack of width that is breaking your top menu.
If I check for undefined and set a zero value if not found then the page starts to work.
e.g.
var rightW = 0;
rightW = $('.top_bar_right').innerWidth();
if (typeof rightW === "undefined") {
rightW = 0;
}
Here is the section to replace with the extra code in place.
/* ---------------------------------------------------------------------------
* Header | Top bar left | Width
* --------------------------------------------------------------------------- */
function mfn_header() {
var rightW = 0;
rightW = $('.top_bar_right').innerWidth();
if (typeof rightW === "undefined") {
rightW = 0;
}
if (rightW && !$('body').hasClass('header-plain')) {
rightW += 10;
}
var parentW = $('#Top_bar .one').innerWidth();
var leftW = parentW - rightW;
$('.top_bar_left, .menu > li > ul.mfn-megamenu').css('width', leftW);
}
Try replacing that section of code and see if it sorts the issue for you. If not then you’ll have to wait for someone more knowledgable in JS to come along 