The children are Chukwudi Nwokobia, 20, Emeka Nwokobia, 17 and Ify Nwokobia, 23, News Agency of Nigeria reports.
The court, however, gave each of the convicts an option of N2, 000 as fine.
The Magistrate, Miss Patricia Okoh, said the prosecution had convinced the court beyond reasonable doubt that the four convicts actually committed the offence.
Okoh said that the evidence presented before the court by the prosecution had assisted the court to pass the judgment.
She warned the convicts to henceforth be of good behaviour, adding that the court would not be lenient with them in the future if arraigned for a similar offence.
The police prosecutor, Mr. Emmanuel Odai, had earlier told the court that the convicts committed the offence on July 20, 2011 at 24, Umkoro Street, Asaba, by slapping their landlord, Mr. Joseph Arinze.
Odai said the offence contravened Section 351 of the Criminal Code Cap C21 Vol. 1, Laws of Delta State, 2006.
The convicts had pleaded not guilty when they were arraigned on July 26, 2011 but changed their plea when the case came up on June 12, and pleaded for leniency.