The task of the criminal law

Problem 6. Starostin with two minor children, 11-year-old Andrew and 8-year-old Alex, took a two-room apartment. In January 1994, this apartment, it was privatized in March 1995 sold it Kukushkin and in June 1995, has died.
The prosecutor asked the court for the benefit of minor children Starostina to declare the contract of sale apartments null and void on the grounds that, in violation of the law of guardianship authorities for the deal did not give consent. The court recognized the transaction invalid and decided to return the apartment minor children, and the buyer - Kukushkina - return 90 thousand. Rub. - The price of the apartment, specified in the contract. The trustee minors Starostin said in court that these children do not have money and can not be, as their late mother and cutting the money squandered. In response Kukushkin said it would not vacate the apartment as long as she does not return all the money. Prosecutor Kukushkina advised to go to court with a claim to the notary for damages, to make sure the transaction is illegal.
What is the legal fate of the apartment?