Answered by Shaykh Amjad Rasheed
What should one do if one is responsible for the funeral and burial of a relative who is non-Muslim?
It is permissible for a Muslim to prepare a non-Muslim’s [h: body] for burial, but it is not permissible for him to perform the funeral prayer for him, or to bury him in Muslim graveyards. He must also avoid what non-Muslims habitually do with their corpses if it is prohibited in our religion.