//filter the employee based on the office id, or you can join the Employee table and Office table and select the employee.
        var emplist = _dbcontext.Employees.where(c=>c.offid == offid ).ToList() 

        //filter the employees report. 
         var queryresult = (from emp in emplist 
                            from t in daysOfMonth
                            select new EmployeeTemp()
                            {
                                Empid = emp.aid,
                                Name = emp.empname,
                                officename =  _dbcontext.Office.where(o=> o.id == emp.offid).Select(o=>o).FirstOrDefault(),                 //find the office name
                                Date = t.Date,
                                ...
                            }).ToList();

         var result = queryresult.GroupBy(c => c.Name).Select(g =>
         {
             var empvm = new EmployeeViewModel();
             empvm.Name = g.Key;
             empvm.OfficeName = g.FirstOrDefault().officename;
             empvm.Attendance = new Dictionary<DateTime, string>();
             foreach (var i in g)
                 empvm.Attendance.Add(i.Date, i.Status);
             return empvm;
         }).ToList();