I composed lines myself but you should read from your file
string[] lines = {"236,Janet, Stones,26300,19/10/2010",
"203,Linda,Phiri,15000,23/10/2010",
"150,Harry,Banda,16700,19/10/2010",
"418,Bridget, Tatianna,16/09/2010",
"210,Joseph,Alonzo,2900,19/10/2010"};
string date = @"19/10/2010";
string pattern = @"((\w|\s)*,){3,4}"+date;
foreach(string str in lines)
{
Console.WriteLine(Regex.Match(str,pattern ).Value.ToString());
}