Is it permissible to open the grave of the deceased after forty days of his death to throw corn kernels and stones on it, and is it permissible for women to visit graves?

Opening a grave to throw grains, perfumes, or clothes into it is an innovation (bid'ah) that has no basis in Islamic law (Shari'ah), and it is a reprehensible act (munkar). A grave is opened only out of necessity, such as forgetting a tool or if something important falls into it. It is not permissible for women to visit graves because the Prophet, peace and blessings be upon him, cursed women who visit graves, and because they are a source of temptation (fitnah) and lack patience, whereas it is legislated for men to remember the Afterlife.