SQL Server : auditing AD Users - how can we identity AD User account from AD Groups
Below is a script that uses xp_login_info (https://msdn.microsoft.com/en-us/library/ms190369.aspx) to get the AD permission paths for each AD user and group with a SQL Server login.

SET NOCOUNT ON;
IF OBJECT_ID(N'tempdb..#results', 'U') IS NOT NULL
     DROP TABLE #results;
CREATE TABLE #results(
      account_name sysname
    , type char(8)
    , privilege char(9)
    , mapped_user_name sysname
    , permission_path sysname NULL
    );

DECLARE @SQL nvarchar(MAX) = (
    SELECT 'INSERT INTO #results EXECUTE xp_logininfo ''' + name + ''', ''all'';'
    FROM sys.server_principals
    WHERE type_desc IN(N'WINDOWS_LOGIN', N'WINDOWS_GROUP')
    FOR XML PATH(''));

EXECUTE(@SQL);

SELECT
      account_name
    , type
    , privilege
    , mapped_user_name
    , permission_path
FROM #results
ORDER BY account_name, mapped_user_name;