Here are the key points I would discuss with the couple:
1. Since the husband has hepatitis B, permanent sterilization methods like vasectomy may not be advisable as it involves surgical procedures.
2. For the wife, IUCD insertion carries a small risk of introducing infection into the uterus. So IUCD may not be the best option.
3. Barrier methods like condoms would help prevent disease transmission but they have higher failure rates compared to other long-acting reversible methods.
4. The safest option would be for the wife to use an injectable contraceptive like DMPA injections which is long-acting and very effective. It does not involve any surgical procedure or devices inside the body.