She said on Friday that she would never forget her last conversation with Zolile.
"She told me she was taking a study break and that was the last time I heard from her."
Khumalo said the first she learnt of Mzolo was after her daughter's death.
He was remanded in custody on Wednesday and caused a furore after his first court appearance in the Durban Magistrate's Court when he signalled the pulling of a trigger as he was led to the holding cells.
"I didn't know him [Mzolo]. I didn't even know his name.
"She didn't say anything about him, which I think is normal ... I wouldn't expect her to speak about her boyfriends with me," Khumalo said.
In a WhatsApp conversation, Zolile told a friend she had ended her relationship with Mzolo.
"We will bury you soon," her friend responded.
Khumalo, 64, said: "Zolile had such big dreams. She wanted to do right by me and the family and renovate the house.
"She would point at passing cars and say when she was done with school she would buy one for me. She loved her family so much."
Khumalo said she continued to brood about Zolile's visit to the family home last weekend - the last time she saw her daughter alive.
The young woman's death has again put the spotlight on gender-based violence in South Africa. The news of Khumalo's killing broke on the day Sandile Mantsoe was found guilty of the 2017 murder of his girlfriend Karabo Mokoena.
Khumalo's death prompted an outcry from the student community and the owners of the Lonsdale residence installed metal detectors at the entrances and banned visitors.
The university is probing how Mzolo, who was not a student at the institution, was apparently able to gain access to the residence after visiting hours with a firearm.
Khumalo was buried in Eshowe yesterday.