Anita P. answered 01/01/22
Anita, ESL and English professor, journalist, photographer, hiker
Always use a comma before that last item in the list, This is the clearest and most logical approach to the grammar of the comma.
The only exception: If you work for a publication whose "House Rules" tell you not to use serial commas, then leave them out, for the sake of the consistency of the publication. Leaving out the final serial comma is not incorrect grammatically---but it can make life more confusing for the reader.