<ul class="class1">
      <div>
        ...
            <span class="spanClass"> Text </span>
        ...
      </div>
</ul>
<div class="class2">
      <div>
        ...
            <span class="spanClass"> Text </span>
        ...
      </div>
</div>

(//ul[@class='class1']//span)[last()]

(//ul[@class='class1'].//span)[last()]

(//ul.//span)[last()]