Is it permissible to give charity and visit the grave for a girl who died in a traffic accident after a relationship developed with her, given that some accused her of fornication, and what is her ruling in Islam?

It is permissible to visit the grave of the deceased woman to supplicate for her and to reflect, and to give charity on her behalf and recite the Quran for her. As for whoever accused her of adultery, he has committed the grave sin of slander, which is forbidden by Islamic law and incurs curses and a painful torment in this world and the hereafter. This crime is further magnified by being against a deceased person. He must repent, seek forgiveness, and supplicate for the deceased woman.