'Ultra vires' means 'beyond the powers'. In administrative law, it refers to an action taken by a public body that is beyond its legal authority. This can be of two types:
Substantive Ultra Vires: When the body makes a rule on a subject matter over which it has no authority.
Procedural Ultra Vires: When the body has the authority to make the rule, but it fails to follow the mandatory procedure prescribed by the parent statute for making that rule (e.g., failure to consult a required body, or failure to publish the draft rules for public comment).
Statement (a) correctly defines it as non-observance of procedural norms. Statement (b) correctly states the consequence: the rule becomes ultra vires and void. Therefore, both (a) and (b) together provide a complete meaning.