Avatar at last post on the index

Hello,
I found a tutorial a long time ago and the result is that there is an avatar from the user on the index who posted the latest message.
No I have the avatar changed into the Hogwarts crest but I want to make it work like, if someone from "slytherin" has posted the latest message, that it turns into the slytherin crest and if someone from ravenclaw has posted the latest message, that it turn into the ravenclaw crest.

What I mean or actually want is: if someone from group #1 has posted, image #1 appears. And if someone from group #2 has posted, image #2 appears (See the pictures). Is this possible?

PICTURE 1:

PICTURE 2:

This is the Javascript I'm using, my forum is PHPBB2.

Code:

$(function(){
 
    if(!window.localStorage) return;
 
    // Avatar par défaut
    var default_avatar= 'http://i.imgur.com/p1oUY1M.png';
 
    // Temps de cache, ici 24 h * 60 m * 60 s * 1000 ms donc un jour
    var caching_time= 24*60*60*1000;
 
    // Temps de cache d'une erreur, ici 60 s * 1000 ms donc une minute
    var caching_error= 60*1000;
 
    var set_avatar= function(id) {
        $('.mini_ava.member'+id).html('<img src="http://i.imgur.com/p1oUY1M.png" />');
    };
 
    var get_avatar= function(id) {
        if(localStorage.getItem('t_ava'+id) < +new Date - caching_time || (localStorage.getItem('d_ava'+id)==default_avatar && localStorage.getItem('t_ava'+id) < +new Date - caching_error))
        {
            localStorage.setItem('d_ava'+id, default_avatar);
            $.get('/u'+id, function (d){
                localStorage.setItem('t_ava'+id,+new Date);
                localStorage.setItem('d_ava'+id, $('#profile-advanced-right .module:first div img:first,.forumline td.row1.gensmall:first > img, .frm-set.profile-view.left dd img,dl.left-box.details:first dd img, .row1 b .gen:first img, .real_avatar img',d).first().attr('src')||default_avatar);
                set_avatar(id);
            });
        }
        return localStorage.getItem('d_ava'+id);
    };
 
    var to_replace= {};
 
    $('dd.lastpost strong a.gensmall, .ipbtable tr td:last-child span strong a.gensmall, .table td.tcr strong a.gensmall, .forumline .row3.over strong a.gensmall').each(function(){
        to_replace[$(this).attr('href').substr(2)]= 1;
        $(this).closest('td,dd').prepend('<div class="mini_ava member'+$(this).attr('href').substr(2)+'"></div>');
    });
 
    for(i in to_replace)
    {
        set_avatar(i);
    };
 
});

I hope anyone could help me?

I'm still looking for someone who could help me?