Redirect (or show the node) taxonomy term page to node, if there's only one node associated with that term
My solution is handle it in hook_preprocess_page(maybe there is another or better solutions but this is good too) 

put this in template.php

first solution(maybe not worked)

function YOURTEMPLATE_preprocess_page(&amp;$variables) {
  if (arg(0) == 'taxonomy' &amp;&amp; arg(1) == 'term' &amp;&amp; is_numeric(arg(2))) {
    $tid = arg(2);
    $items = taxonomy_select_nodes($tid;
    if(count($item)==1){
         drupal_goto('node/'.$items[0]-&gt;nid);
     }
    }
}


Alternative solution  

function YOURTEMPLATE_preprocess_page(&amp;$variables) {
  if (arg(0) == 'taxonomy' &amp;&amp; arg(1) == 'term' &amp;&amp; is_numeric(arg(2))) {
    $tid = arg(2);
    $items = taxonomy_select_nodes($tid);
    if(count($items)==1){

         //another solution is set a variable in preprocess and in page.tpl.php or your taxonomy tempalte page redirect it 
         $variables['soheil_redirect_tax'] = array('path' =&gt; url('node/'.$items['nid']));

    }
  }


if first solution (drupal_goto) not worked in page.tpl.php or your custom template for terms page handle redirect(I mean in page.tpl.php file or taxonomy--term.tpl.php file) with 

 if(isset($soheil_redirect_tax)){
    drupal_goto($soheil_redirect_tax['path']);
 }