A quick example of how to create a custom WordPress widget that will show the current months leaderboard based on myCRED Points. Requires myCRED 1.4 or higher.

mycred-monthly-leaderboard

/**
 * Custom myCRED Widget: This months leaderboard
 * This widget will show this months leaderbaord with the option to set
 * a title, the number of users to include and if it should be visible for
 * non-members.
 * @install Paste into your theme or child-themes functions.php file or custom plugin.
 * @author Gabriel S Merovingi
 * @version 1.1.1
 */
add_action( 'mycred_widgets_init', 'mycred_load_this_months_leaderboard_widget' );
function mycred_load_this_months_leaderboard_widget() {

	if ( ! class_exists( 'myCRED_Widget_This_Months_Leaderboard' ) ) {
		class myCRED_Widget_This_Months_Leaderboard extends WP_Widget {

			// Constructor
			public function __construct() {

				parent::__construct(
					'mycred_widget_this_months_leaderboard',
					sprintf( __( '(%s) This Months Leaderboard', 'mycred' ), mycred_label() ),
					array(
						'classname'   => 'widget-mycred-this-months-leaderboard',
						'description' => __( 'Show the leaderboard for a given timeframe.', 'mycred' )
					)
				);

			}

			// Widget Output (what users see)
			public function widget( $args, $instance ) {

				extract( $args, EXTR_SKIP );

				// Check if we want to show this to visitors
				if ( $instance['show_visitors'] == 0 && ! is_user_logged_in() ) return;

				// Get the leaderboard
				$leaderboard = $this->get_leaderboard( $instance['number'], $widget_id );

				// Load myCRED
				$mycred = mycred();

				// Start constructing Widget
				echo $before_widget;

				// Title (if not empty)
				if ( ! empty( $instance['title'] ) ) {
					echo $before_title;
					// Allow general tempalte tags in the title
					echo $mycred->template_tags_general( $instance['title'] );
					echo $after_title;
				}

				// Construct unorganized list for each row
				echo '<ul class="mycred-this-months-leaderboard">';
				foreach ( $leaderboard as $position => $data ) {
					$avatar = get_avatar( $data->user_id, 32 );
					echo '<li>' . $avatar . $data->display_name . ' with ' . $mycred->format_creds( $data->total ) . '</li>';
				}
				echo '</ul>';

				echo $after_widget;

			}

			// Widget Settings (when editing / setting up widget)
		 	public function form( $instance ) {

				$title         = isset( $instance['title'] ) ? esc_attr( $instance['title'] ) : __( 'This Months Leaderboard', 'mycred' );
				$number        = isset( $instance['number'] ) ? abs( $instance['number'] ) : 5;
				$show_visitors = isset( $instance['show_visitors'] ) ? 1 : 0;

?>
<p class="myCRED-widget-field">
	<label for="<?php echo esc_attr( $this->get_field_id( 'title' ) ); ?>"><?php _e( 'Title', 'mycred' ); ?>:</label>
	<input class="widefat" id="<?php echo esc_attr( $this->get_field_id( 'title' ) ); ?>" name="<?php echo esc_attr( $this->get_field_name( 'title' ) ); ?>" type="text" value="<?php echo esc_attr( $title ); ?>" />
</p>
<p class="myCRED-widget-field">
	<label for="<?php echo esc_attr( $this->get_field_id( 'number' ) ); ?>"><?php _e( 'Number of users', 'mycred' ); ?>:</label>
	<input id="<?php echo esc_attr( $this->get_field_id( 'number' ) ); ?>" name="<?php echo esc_attr( $this->get_field_name( 'number' ) ); ?>" type="text" value="<?php echo $number; ?>" size="3" class="align-right" />
</p>
<p class="myCRED-widget-field">
	<input type="checkbox" name="<?php echo esc_attr( $this->get_field_name( 'show_visitors' ) ); ?>" id="<?php echo esc_attr( $this->get_field_id( 'show_visitors' ) ); ?>" value="1"<?php checked( $show_visitors, 1 ); ?> class="checkbox" /> 
	<label for="<?php echo esc_attr( $this->get_field_id( 'show_visitors' ) ); ?>"><?php _e( 'Visible to non-members', 'mycred' ); ?></label>
</p>
<?php if ( isset( $this->id ) && $this->id !== false ) : ?>
<p class="myCRED-widget-field">
	<input type="checkbox" name="<?php echo esc_attr( $this->get_field_name( 'reset_leaderboard' ) ); ?>" id="<?php echo esc_attr( $this->get_field_id( 'reset_leaderboard' ) ); ?>" value="1" class="checkbox" /> 
	<label for="<?php echo esc_attr( $this->get_field_id( 'reset_leaderboard' ) ); ?>"><?php _e( 'Reset Leaderboard', 'mycred' ); ?></label>
</p>
<?php

				endif;

			}

			// Save Widget Settings
			public function update( $new_instance, $old_instance ) {

				$instance = $old_instance;
				$instance['number']        = absint( $new_instance['number'] );
				$instance['title']         = sanitize_text_field( $new_instance['title'] );
				$instance['show_visitors'] = ( isset( $new_instance['show_visitors'] ) ) ? $new_instance['show_visitors'] : 0;
			
				if ( isset( $new_instance['reset_leaderboard'] ) && $this->id !== false ) {
					delete_transient( 'mycred_tml_' . $this->id );
				}

				return $instance;

			}

			// Grabs the leaderboard
			public function get_leaderboard( $number = 5, $widget_id = '' ) {

				// Get transient
				$leaderboard = get_transient( 'mycred_tml_' . $widget_id );
			
				// If transient does not exist or a new number is set, do a new DB Query	
				if ( $leaderboard === false || $number != 5 ) {

					// Load the wpdb class
					global $wpdb;
				
					$mycred         = mycred();
					$now            = current_time( 'timestamp' );
					$start_of_month = strtotime( "first day of this month" );

					$leaderboard    = $wpdb->get_results( $wpdb->prepare( "
						SELECT m.user_id, u.display_name, sum( m.creds ) AS total 
						FROM {$mycred->log_table} m 
						LEFT JOIN {$wpdb->users} u 
							ON u.ID = m.user_id 
						WHERE ( m.time >= %d AND m.time <= %d AND m.creds > 0 ) 
						GROUP BY m.user_id 
						ORDER BY total DESC LIMIT 0,%d;", $start_of_month, $now, $number ) );

					// Save results till end of month
					$lifespan = (int) strtotime( "last day of this month" ) - $now;

					set_transient( 'mycred_tml_' . $widget_id, $leaderboard, $lifespan );

				}
			
				return $leaderboard;

			}

		}

	}

	register_widget( 'myCRED_Widget_This_Months_Leaderboard' );

}