string clusterName = "app-server.local";
string custerGroupResource = "cluster.server.local";

ConnectionOptions options = new ConnectionOptions
{
    Authentication = AuthenticationLevel.PacketPrivacy
};

ManagementScope s = new ManagementScope("\\" + clusterName, options);

ManagementPath p = new ManagementPath("Mscluster_Clustergroup.Name='" + custerGroupResource + "'");

using (ManagementObject clrg = new ManagementObject(s, p, null))
{
    clrg.Get();
    Console.WriteLine(clrg["Status"]);
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System;
using System.Management;

namespace  MyNamespace
{
public class ClusterAdmin
{
    [MTAThread]
    public static void Main()
    {
        string clusterName = "MyCluster"; // cluster alias
        string custerGroupResource = "FS_Resource1"; // Cluster group name
        ConnectionOptions options = new ConnectionOptions();
        options.Username = "ClusterAdmin"; //could be in domainuser format
        options.Password = "HisPassword";

        // Connect with the mscluster WMI namespace on the cluster named "MyCluster"
        ManagementScope s = new ManagementScope("\\" + clusterName + "\root\mscluster", options);
        ManagementPath p = new ManagementPath("Mscluster_Clustergroup.Name='" + custerGroupResource + "'");

        using (ManagementObject clrg = new ManagementObject(s, p, null))
        {
            // Take clustergroup off line and read its status property when done
            TakeOffLine(clrg);
            clrg.Get();
            Console.WriteLine(clrg["Status"]);

            System.Threading.Thread.Sleep(3000); // Sleep for a while

            // Bring back online and get status.
            BringOnLine(clrg);
            clrg.Get();
            Console.WriteLine(clrg["Status"]);
        }
    }
    static void TakeOffLine(ManagementObject resourceGroup)
    {
        ManagementBaseObject outParams =
        resourceGroup.InvokeMethod("Takeoffline", null, null);
    }
    static void BringOnLine(ManagementObject resourceGroup)
    {
        ManagementBaseObject outParams =
        resourceGroup.InvokeMethod("Takeoffline", null, null);
    }
}
}