Bafana are currently in Ouagadougou for their opening Group D Wolrd Cup qualifier against Burkina Faso on Saturday evening.
Acccording to SowetanLive, Mathoho has been in contact with his family from withing camp following the passing his younger brother on Sunday.
Mashaba has since lauded the 26-year-old for opting to remain on duty, while offering his condolences to the bereaved family.
"We are sitting here with a problem," Mashaba said. "Mathoho came to us and told us that his younger brother has passed on.
"We need to encourage him and we appreciate that he says he will stay with the team and carry on.
"We would like to say to the family that we are with them at this point in time and we would like to thank them for allowing Mathoho to come here and finish his commitment with the national team."
'Tower' is likely to start the match on Saturday but could miss their friendly fixture against Ghana next Tuesday, as he is expected to return to his family upon his arrival back in the country.