offering funeral ceremonies for the dead is impermissible, so you have to repay (Part No. 16; Page No. 447) the money that you spent on the funeral ceremony to the heirs.
any permissible profits yielded from the invested money belong to the heirs, thus, it should be distributed to them unless they willingly give them up.
you should pay the due Zakah for the year 1983, and that of your mother to the entitled persons mentioned in the saying of Allah (Exalted be He):
As-Sadaqât (here it means Zakât) are only for the Fuqarâ’ (poor), and the Masâkin (needy) and those employed to collect (the funds)
The same goes for the rest of the Sadaqah; for none of this money should be invested; rather, it should be paid to them. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.