(b) That's right. A and B are husband and wife. In the general law, if a wife guarantees her husband's debts without understanding the essential effect of the transaction, and without getting a financial benefit from the transaction, the guarantee can be set aside on grounds of unconscionable dealing, unless the creditor has ensured that the wife has received independent legal advice before agreeing to the legal obligations.
The need for independent advice is necessary because the relationship between spouses is one of trust and confidence, and it is therefore unlikely that a full and proper explanation of the transaction will have been demanded or given between the spouses. This puts the wife at a disadvantage and makes her unable to judge whether it is in her best interests to enter into the transaction.
In the present case, B has had independent legal advice before executing the mortgage. This advice would most likely ensure that B was properly informed and able to judge what was in her own best interests. The contract would probably not be set aside in these circumstances.