My dad has had a drinking problem for most his life, but he stopped for a while. Recently we found bottles at his house again. Do you think that because my mother died last year and he is living alone thats why hes drinking again?

Yeah that could be a big enabler, put yourself in his shoes. If you lost the love of your life, wouldn't you try and fill that void with something else, maybe he's just trying to feel better with alcohol, he must be going through a lot. Try talking to him about it and making him feel like he's not alone.

Yeah I reckon so, hes found himself at a point again where he has no control, he couldnt control the death of your mother and naturally he will be extremely emotional, confused and looking for something to block that pain, and alcohol can do that, though for a short time. Try and discuss it with him, dont even mention the alcohol at first but try and get him to open up, he is still grieving, when you can get him to be open and express himself then talk to him about the alcohol.