How to help my Mum with her grieving?

My Grandad died at the age of 80 in late January, I've dealt with it quite well and have come to terms with it all to be honest but my Mum is really struggling, I hear her writhing about and crying some nights and even though I try to help nothing seems to be good enough. She keeps saying she wants him back and deep down she knows she can't do anything and I know everyone is different when it comes to these situations (I had to see a counselor when my Dad's Mum died) but I just wondered if anyone had any advise as to how to help her. She normally gets upset on a night or if she's had a few glasses or wine if that has anything to do with it??