Placing a Deceased Person's Garment on the Grave

Honored Rabbi, hello! 

I was told to place my mother's garment on her grave during the 11th month, take it back, and in the year to bring the garment again, place it on the grave, and leave it there forever. I asked why, and they were not able to explain to me the meaning of the custom. And should one do so? 

Thank you very much, Dina