You can purchase a burial expenses insurance policy on your brother if you have an Insurable Interest in him, meaning - if you either rely on him for some means of financial support, or he owes you some money, or you would have to pay for his final expenses should he pass away.
If you were to suffer any financial cost due to his death, you may have an insurable interest, which is required in order to buy life insurance on someone else.
Learn more about buying burial insurance on your brother.