In wpresidence/libs/listing_functions.php at line 324 add this code

$url= get_post_meta($post_id,'property_latitude',true).','.get_post_meta($post_id,'property_longitude',true);
$google_map_url = "https://www.google.com/maps/@".$url;

or

$url= get_post_meta($post_id,'property_latitude',true).','.get_post_meta($post_id,'property_longitude',true);
$google_map_url = "http://maps.google.com/?q=".$url;

​It should look like this