Question

either my sister or my friends....... arriving today.(is/are)


with reason....​

Answer 1

Explanation:

either my sister or my friends is arriving today with reason

Answer 2

Either my sister or my friends is arriving today.

Explanation: Because it is clear that not both of them will come together, whereas only one from both of them will cime so, in conclusion only one personality will arrive. Thus, we will use is.