Many thanks for your information. I rechecked all the available official information I can find online and the ejabberd source, I still unable to find anything mention on XEP-0084 or avatar (only XEP-0153 and vCard is mentioned). I have referred to the following documents:
c. Home server-ejabberd v16.08: mod_pubsub.erl and pubsub.hrl (include file)
I see someone mention the support of user avatar in this post
Not sure if ejabberd has actually treated XEP-0084 as PEP without referring it as XEP-0084
The “pep” plugin adds extention to handle Personal Eventing Protocol
([`XEP-0163`](http://xmpp.org/extensions/xep-0163.html)) to the PubSub
engine. Adding pep plugin to PubSub make it handle PEP automatically.
Anyway I will try to test with ejabberd on XEP-0084 and see if it does response to Publishing avatar metadata
Thanks again for the info.