Subject to the provisions of section 20, every claim of the nature specified in section 17 against the ward or his estate other than debts due to and liabilities incurred in favour of the Government, which is not notified under section 17, shall be deemed for all purposes and on all occasions, whether during continuance of the superintendence of the Court of Wards or afterwards, to have been duly discharged:
Provided that, if the claimant can show sufficient cause for failure to comply with the provisions of section 17, the Collector shall receive his claim, and the claim so received shall be deemed to have been notified under section 17:
Provided also that the provisions of this section shall not be deemed to extinguish any such claim in any case in which the Court of Wards after assuming the superintendence of such estate releases the same from its superintendence without discharging the liabilities thereof, in the manner provided in this chapter:
Provided further, that nothing in this section shall apply to a mortgagee in possession of immovable property of the ward.