(b) That's right. Where a plaintiff who has suffered personal injury is cared for at home by family members or friends acting voluntarily and without payment the defendant is nevertheless liable under the common law to pay damages for the fair and reasonable value of those services. This value is calculated by reference to the market cost or value of those services.
If the person providing the gratuitous services is the defendant (something not uncommon in car accident cases) the situation is treated as exceptional and the courts have tended to deny the plaintiff the right to recover the market value of such services. Otherwise the defendant would arguably be paying twice.
NOTE: The common law approach has been superseded in some Australian jurisdictions by legislation that removes or limits a plaintiff's right to claim the value of services rendered gratuitously.