public class Account_CloneCasesOnAnniversary implements   Database.Batchable<SObject>
{
    String errors = '';
    integer todayday = date.today().day();
    Integer currentmonth = date.today().month();

 public Database.QueryLocator start(Database.BatchableContext bc)
{
   return Database.getQueryLocator('SELECT Anniversary__c,(Select Id from cases order by CreatedDate),Id from Account WHERE DAY_IN_MONTH(Anniversary__c) =:todayday AND CALENDAR_MONTH(Anniversary__c ) =: currentmonth') ;
}

 public void execute(Database.BatchableContext bc, List<Account> scope)
 {
    if(scope.isEmpty()) return;
    List<Case> caseToCreateList = new List<Case>();
    List<Task> taskToCreateList = new List<Task>();

    system.debug('Scope is'+scope);

     for(account objS : scope){

         for(task objT : scope) {

             system.debug('Account with case'+objS);

        if(objS.cases.size() > 0 && objT.Task.size() >0 )
        {

            system.debug('aAccount.cases.size()'+objS.cases.size());
            list<Case> lstCase = new list<Case>();
            for(Case objcase : objS.cases){
                Case cloneCase = new Case();
                cloneCase  = objcase.clone();

                // collecting the Cases to create
                caseToCreateList.add(cloneCase);
            }

            for(Task objTask : objT.Task) {

                Task cloneTask = new cloneTask();
                cloneTask=objTask.clone();

                taskToCreateList.add(cloneTask);

            }

        }
         system.debug('caseToCreateList'+caseToCreateList);
     }
   }

       if(!caseToCreateList.isEmpty()) 
       { 

         Database.SaveResult[] srList = Database.insert(caseToCreateList, false);
         Integer index = 0;
         system.debug('---srList  first'+ srList );

         for(Database.SaveResult result : srList )
         {
            if(!result.isSuccess())
            {
                String errMsg = result.getErrors()[0].getMessage();

            } // End Inner If
            index++;
          } // End for
         } // End Outer If
       } // End try


public void finish(Database.BatchableContext context)
{

    }
   }
  }