BuddyPress.org

Hey,
you can add this in functions.php

$not_logged_in_user = '';
function prevent_subscriber_from_members() {
    global $not_logged_in_user;
    if (
        // Look for  /members/ page
        stripos($_SERVER['REQUEST_URI'],'/members/') !== false
        ) {         
        // If subscriber, redirect on home page
        if (!is_user_logged_in() ) {              
            if ($not_logged_in_user == '') { $not_logged_in_user = get_option('home'); }            
            // Send a temporary redirect
            wp_redirect($not_logged_in_user,302);            
        }           
    }       
}
add_action('init','prevent_subscriber_from_members',0);

It checks if the user is logged in. If not, redirects him to home page