Would I be able to get a military protective order or military no contact order against a civilian/civilians who aren’t military affiliated?

You need a civilian restraining order. Your Commander has no jurisdiction over your in laws

MPO only applies on base. If you live on base and they don't have any DOD ID, they can't get on base unless someone with a DoD ID sponsors them.

If you live off base go apply for a protection order at your county courthouse. However you'll need proof they're actually harassing you to get a permanent protection order.

MPO's don't have any affect on Civilians as effectively what they are is a written order from a commander stipulating that one Soldier is not to make contact with another person which may or may not be military themselves without informing the commander or designated individual usually the 1SG or CSM prior to the contact or of any unintended contacts.

You should reach out to your local JAG office regarding any legal advice pertinent to this situation, and they will likely inform you to contact a Civilian attorney and/or local court and law enforcement agency regarding an Order of Protection, No Contact Order, or Restraining Order as it applies to your respective State.

It would do you well to begin documenting any threatening or harassing incidents involving the other party for the future.