Steph Njuguna has been captured viciously attacking her boyfriend Jeffrey Ndegwa for breaking up wit.
Kate Legodi, 75, owner of a daycare centre in Winterveldt, north of Pretoria, was found with a cracked skull.
Police say she was hacked several times over the head with a sharp object.
Her son, 43, has been arrested for the murder. Her 40-year-old adopted son disappeared soon after the murder and police are looking for him.
Loate police spokesman warrant officer Llifi Ramatlo said Legodi's body was discovered by one of her employees at about 11am last Thursday. It was found on the floor of her adopted son's bedroom, lying in a pool of blood.
Ramatlo said the suspect was due to appear in the GaRankuwa Magistrate's Court today.
Sandy Legodi, one of the victim's sons , described his brother as "troublesome". He said he "always picked fights with our mother whenever he needed money".
Sandy said employees were surprised when they arrived on Thursday morning and found the creche still closed. When there was still no sign of her hours later, they called him to say that his mother was missing.
He said they phoned him again a few minutes later and told him his mother was dead.
Legodi's death has shocked the GaRankuwa, Mabopane and Winterveldt Forum of which Legodi was a member.
"Sis Kate was our mother, sister and aunt, who showed us the ropes of running a successful daycare centre," said Lenah Segwai, deputy chairwoman of the GMW.