The most popular oil used in mummification is the cedar oil, that is an oil from the cedar tree. But a cedar oil is not a palm oil - so it's probably not what the question meant.
Some sources mention " bitumen" as a palm-oil used for mummification and I think that this is what the question asks for. However, bitumen is not exactly a palm oil- it's more simiar to asphalt, which we today use in building roads.