public class Records
        {
            public int Id { get; set; }
            public string Text { get; set; }
            public string Group { get; set; }
            public DateTime Date { get; set; }
        }

        static void Main(string[] args)
        {
            var records = new List<Records>
            {
                new Records {Id = 1, Text = "Some text 1", Group = "A", Date = new DateTime(2015, 01, 01)},
                new Records {Id = 2, Text = "Some text 2", Group = "A", Date = new DateTime(2015, 01, 08)},
                new Records {Id = 3, Text = "Some text 3", Group = "B", Date = new DateTime(2015, 01, 04)},
                new Records {Id = 4, Text = "Some text 4", Group = "B", Date = new DateTime(2015, 01, 09)},
                new Records {Id = 5, Text = "Some text 5", Group = "C", Date = new DateTime(2015, 01, 07)},
                new Records {Id = 6, Text = "Some text 6", Group = "C", Date = new DateTime(2015, 01, 06)},
				new Records {Id = 6, Text = "Some text 6", Group = "E", Date = new DateTime(2018, 01, 06)}
            };

            var latests = records.GroupBy(p => p.Group)
								 .Select (o => o.OrderByDescending( g => g.Date)
								 				.FirstOrDefault()
										 )
								 .Where( x => x.Date >= records.OrderBy( g => g.Group)
								                               .ThenByDescending( g => g.Date)
															   .Take(1)
															   .Max(g => g.Date)  ) ;
															   
			latests.Dump();
			
        }