Answer: b. change his passwords and store them in a password manager.
Explanation:
Sometime people are able to access our details and engage in nefarious acts with them such as using our credit cards to buy things such as is the case with Hussein above.
They may have gained this information by getting into Hussein's private devices such as his private computer or phone. In order to mitigate the chances of this happening again, he should change his password so that they will not be able to access details of the new card.