Query Multiple meta

The query as written will retrieve posts with the post type custom_type_houses that are For Rent OR in Arusha. If you want just houses that are both For Rent AND in Arusha you will need to change 'relation' => 'OR' in your meta query to 'relation' => 'AND', like so:

<?php
    $args = array(
        'post_type' => 'custom_type_houses',
        'meta_query' => array(
            'relation' => 'AND',
            array(
                'key'     => 'custom_meta_location',
                'value'   => 'Arusha',
                'compare' => '=',
            ),
            array(
                'key'     => 'custom_meta_status',
                'value'   => 'For Rent',
                'compare' => '=',
            ),
        ),
    );

    $query = new WP_Query( $args );

    while ( $query->have_posts() ) {
        $query->the_post();
    }
?>