Use WP_Query
‘s category__and
:
$args = array(
'posts_per_page' => 5,
'category__and' => array( 93, 85 )
);
$my_query = new WP_Query( $args );
while( $my_query->have_posts() ):
$my_query->the_post();
the_title();
endwhile;
wp_reset_postdata();