In the determination of the benefits to be awarded any member of the militia or his dependents under the provisions of Section 340, it shall be conclusively presumed that the average yearly earning of such injured or deceased member is not less than two thousand five hundred dollars ($2,500). Any injury, death, or disability shall be deemed to have been suffered in line of duty unless the same resulted from misconduct or disobedience of lawful orders by the injured or deceased member.