As I heard when I was in TN, there is a pariharam for this. Instead of meeting your mother at home, you can meet her in any temple with some water in a "sombu". Both of you should look at the water first and then can see each other. Subsequently you can go to her house and do other things as you wish. I do not know the significance of this but this is what I heard. By doing this, you are also following the old customs and at the same time arriving at a practical solution.
Hope this solution may help you to certain extent. Very sorry about the demise of your father.
Venkat K