EasyBlog 5.0.17 - PHP Fatal Error prevents post submittal

What happens:
I am unable to submit blog posts whether "Allowed To Publish Post" is set to Yes or No.
When I click Submit for Approval or Publish Post, it pops up the Saving... box, the spinner spins a couple times then the box disappears and the green banner shows, but no text is displayed in the green banner message.

What I have tried:

• For each test, I simply enter the title as Test and in the body I erased Enter your text here... and typed testing 123. So I don't think the issue was due to post content.
  
• Changed Joomla! template to Protostar to troubleshoot template conflicts; no fix.
  
• I turned on Maximum error reporting for Joomla and after failing to save, rather than being blank the green banner message then showed something about Invalid JSON at column 1 line 1.
  
• I ssh into the web server and check apache error_log and found the following:
  
PHP Fatal error: Call to undefined function mb_convert_encoding() in /var/www/html/administrator/components/com_easyblog/includes/blocks/handlers/abstract.php on line 150, referer: http://***/index.php/articles?view=composer&tmpl=component

• I have to comment out line 150 in abstract.php to allow the post to save properly. With line 150 commented out, everything seems to work as it should.
  

149   // convert html entities back to it string. e.g.  back to empty space

150   //$content = html_entity_decode(mb_convert_encoding(stripslashes($content), "HTML-ENTITIES", 'UTF-8'));

It appears the syntax is wrong at least for my version of PHP and/or apache, but I won't pretend to know enough to try and fix it the right way . I migrated this site to a web host running older PHP version and I did not have this issue and did not have to comment out line 150.

Here is my Joomla! System Information:
PHP Built On Linux centOSv6.5 2.6.32-504.16.2.el6.x86_64 #1 SMP Wed Apr 22 06:48:29 UTC 2015 x86_64
Database Version 5.1.73
Database Collation latin1_swedish_ci
PHP Version 5.4.41
Web Server Apache/2.2.15 (CentOS)
WebServer to PHP Interface apache2handler
Joomla! Version Joomla! 3.4.3 Stable [ Ember ] 2-July-2015 16:00 GMT
Joomla! Platform Version Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT
User Agent Mozilla/5.0 (Windows NT 6.1; rv:39.0) Gecko/20100101 Firefox/39.0

If you would like more information I would be happy to provide it. Sorry I cannot provide site access as this is an internal site and not accessible from the internet.

Can you suggest a proper syntax for line 150 and I will try it and report back?

Thanks