C#

public static string gridChallenge(List grid) {

List<string> arrangedGrid = new List<string>();

    foreach(string s in grid)
    {
        arrangedGrid.Add(new string(s.OrderBy(x=>x).ToArray()));

    }               

    for(int row = 0; row < arrangedGrid.Count - 1; row++)
    {
        for (int column = 0; column < arrangedGrid[0].Count(); column++)
        {
            if(arrangedGrid[row][column] > arrangedGrid[row + 1][column])
            {
                return "NO";
            }
        }
    }

    return "YES";

}