You can fire query only by 'meta_key'=> 'selsubcat'
without meta_value
`and you will get all subcategories. Then you should loop outside you tab with some increment(maybe a name of category or numeric id) something like this:
<?php
foreach( $posts as $post ): setup_postdata( $post ); ?>
<div id="tabs-<?php the_ID(); ?>">
<table id="table-<?php the_ID(); ?>" class="display" cellspacing="0" width="100%">
<tbody>
<tr>
<td class="hidden"><?php the_ID(); ?></td>
<td><span class="product-image" style="background:url(<?php the_field('image'); ?>);"></span></td>
<td><?php the_field('code'); ?></td>
<td><?php the_field('description'); ?></td>
<td><?php the_field('cost_price'); ?></td>
<td><input type="text" /></td>
<td><input type="text" /></td>
<td><input type="button" class="add-row" name="add-row" value="Add"></td>
</tr>
</tbody>
<?php $product_increment++; endforeach; ?>
</table>
</div>
</div>