result = authContext.AcquireTokenAsync(resourceHostUri, clientId, new UserCredential(hardcodedUsername, hardcodedPassword)).Result;

string hardcodedUsername = "username";
        string hardcodedPassword = "password";

        string tenant = "tenantId@onmicrosoft.com";
        string clientId = "clientId";
        string resourceHostUri = "https://management.azure.com/";
        string aadInstance = "https://login.microsoftonline.com/{0}";

        string authority = String.Format(CultureInfo.InvariantCulture, aadInstance, tenant);


        authContext = new AuthenticationContext(authority);

        AuthenticationResult result = null;
            try
            {

                result = authContext.AcquireTokenAsync(resourceHostUri, clientId, new UserCredential(hardcodedUsername, hardcodedPassword)).Result;
            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.WriteLine(ex.Message);
            }

            return result;