What remedies are available in the last instance?

ElectoralAct, 2012

Article 63

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4) Where the ReturningOfficer decides that a nomination paper is invalid, he shall endorse and signon the paper the fact and the reasons for the decision.
(5) A candidate aggrievedby the decision of the Returning Officer as to the validity or otherwise of a nomination paper may appeal tothe Electoral Commission, which may uphold the decision of the Returning Officer or reverse it.
(6) The decision of the Returning Officer or, in the case of an appeal, theElectoral Commission, on the validity of a nomination shall be final and shallnot be questioned in any proceeding whatsoever, except by way of an election petition. […]

140. (1) A petition complaining of an undue return or undue election of aMember of Parliament or a member of a local council, in this Act called anelection petition, maywithin twenty-one days from the date of the publication of the result of theelection in the Gazette be presented to a Judge of the High Court by anyone or more of the following persons:-

(a) A person who voted or had a right to vote at the election to which feepetition relates;
(b) A person who claims to have had a right to be returned or elected at theelection; or
(c) A person who alleges himself to have been a candidate at that election.
(2) A person presenting an election petition shall forthwith deliver a copy ofit to the Electoral Commission.

145. (1) An appeal shall lie to the Court ofAppeal from the determination of the High Court upon an election petition, or aproceeding of the High Court taken under section 138 at the suit of a Party tothe petition or proceedings, and the decision of the Court of Appeal on theappeal shall be final to all intents and purposes.

(2) Notwithstanding anyprovisions to the contrary, the Court of Appeal shall not entertain an appealunder this section unless notice of the appeal has been given within fourteen days of thedetermination in question.
(3) At the time of filing the notice of appeal, the appellant shall give security for the payment ofall costs, charges and expenses which may become payable by him to anywitnesses summoned on his behalf or to a respondent, in an amount and given inthe manner, as the Court, may order; and in the event of a failure to complywith the order, no proceedings shall be heard on the appeal.

146. (1) If the High Court determines that acandidate returned as elected was not duly elected and that the election wasvoid, then the candidate’s seat shall become vacant from the time of the noticeof decision of the High Court and if notice of appeal from that decisionappeal, has been given within fourteen days, the seat shall remain vacant forthe period until the determination of the Court of Appeal is given on theappeal or the appeal is abandoned.

(2) Where the question to be decided by the Court’of Appeal concerns an election to or the right to remain a member ofParliament, the Registrar of the Court of Appeal shall certify the decision in writing to the Speaker andthe Electoral Commission.
(3) Where the High Court has determined that a candidate was duly returned orelected, or that the election was void, and no notice of appeal has been givenagainst that determination within fourteen days, or where on appeal the Courtof Appeal has determined that a candidate was duly returned or elected, or thatthe election was void, then the Speaker shall publish by notification in theGazette whether the candidate whose return or election is questioned is dulyreturned or elected or whether the election is void.
(4) If the election is declared void, another election shall be held.