The very best thing you can do to help your father now is to simply sit when you have the time, and to do your best to keep a bright and positive mind throughout your day. He will be in your heart and since ultimately there is no separation or dividing up of existence, your hearts are identical. If the relationship with him has been troublesome this doesn't matter, let what ever is there be there without judgements.
You are right, we do not have a specific practice around death, or more correctly meditations focusing on the impermanence of the body. That all is fairly much covered in just sitting.
In terms of your own acceptance of his sudden death you will have to realize that there is a level of shock which will take time to work it's way through.
As for what you can do at home now. You can put his photograph on your altar and perhaps put some kind of non perishable food/drink which he would have liked there too. You can recite one of the compassion scriptures daily and offer the merit of the recitation for his benefit.
The advice above is fairly standard however it does assume an understanding of the practice of meditation and the Buddhist Precepts.