From the VA site the regulation is specific in its intent to not provide for reserve and guard soldiers
MEMORIAL HEADSTONE OR MARKER - Furnished upon application for installation in a cemetery only to commemorate any eligible veteran whose remains have not been recovered or identified, were buried at sea, donated to science, or cremated and the remains scattered; may not be used as a memento.
WHO IS ELIGIBLE - Any deceased veteran discharged under conditions other than dishonorable. A copy of the deceased veteran's discharge certificate (DD Form 214 or equivalent) or a copy of other official document(s) establishing military service must be attached. Service after September 7, 1980, must be for a minimum of 24 months continuous active duty or be completed under special circumstances, e.g., death on active duty. Persons who have only limited active duty service for training while in the National Guard or Reserves are not eligible unless there are special circumstances, e.g., death while on active duty, or as a result of training.
Another policy which should be relooked considering the changed nature of Guard and Reserve duty.