Hello,
Regarding your issue, it seems like in Joomla 3.7, somehow the SQL that return menu items for EasySocial is returning menu item for backend as well
We've rectified this issue and I've applied the fix on your site. Now the URL is working correctly.
For anyone that having the same issue, please download the attached router.php file and copy this file to folder 'JOOMLA/administrator/components/com_easysocial/includes/' and overwrite the existing 'router.php' file. Remember to backup the original file first before you overwrite the file.
The same fix will be added into EasySocial 2.0.17
Hope this help and have a nice day.