mysql: show which users have permissions to a DB
Have a look at the Query 

SELECT
 md.host `Host`,
 md.user `User`,
 md.db `Database`,
 REPLACE(RTRIM(CONCAT(
 IF(md.Select_priv = 'Y', 'Select ', ''),
 IF(md.Insert_priv = 'Y', 'Insert ', ''),
 IF(md.Update_priv = 'Y', 'Update ', ''),
 IF(md.Delete_priv = 'Y', 'Delete ', ''),
 IF(md.Create_priv = 'Y', 'Create ', ''),
 IF(md.Drop_priv = 'Y', 'Drop ', ''),
 IF(md.Grant_priv = 'Y', 'Grant ', ''),
 IF(md.References_priv = 'Y', 'References ', ''),
 IF(md.Index_priv = 'Y', 'Index ', ''),
 IF(md.Alter_priv = 'Y', 'Alter ', ''),
 IF(md.Create_tmp_table_priv = 'Y', 'Create_tmp_table ', ''),
 IF(md.Lock_tables_priv = 'Y', 'Lock_tables ', ''),
 IF(md.Create_view_priv = 'Y', 'Create_view ', ''),
 IF(md.Show_view_priv = 'Y', 'Show_view ', ''),
 IF(md.Create_routine_priv = 'Y', 'Create_routine ', ''),
 IF(md.Alter_routine_priv = 'Y', 'Alter_routine ', ''),
 IF(md.Execute_priv = 'Y', 'Execute ', ''),
 IF(md.Event_priv = 'Y', 'Event ', ''),
 IF(md.Trigger_priv = 'Y', 'Trigger ', '')
 )), ' ', ', ') AS `Privileges`
FROM
 mysql.db md WHERE db='DB_NAME';


It may give result as you desired.

For Reference have a look at How to Get a List of Permissions of MySQL Users.