"Monica (Fenty) is moving in to keep an eye on her. Rihanna's dad, Ronald, was a crack addict. Monica's refusing to let her go down that path," a source told.
Rihanna was recently hospitalised after suffering from exhaustion and dehydration. She tweeted a picture of herself attached to a drip in a hospital.
However, after a brief stay in the undisclosed medical centre, the 24-year-old was discharged and allowed to fly back home.
One reason why she may be suffering with exhaustion is her extensive workout regime, with her trainer Harley Pasternake claiming she will even hit the gym in the middle of the night if necessary.