"The Home Secretary has promised a review of sentencing. This needs to be delivered urgently to ensure killers like Philpott serve the long sentences their horrific crimes deserve."
Mairead's mother Vera, who has cut ties with her daughter, told The Sun she was appalled her daughter was released early, saying: "I don't want her near my door.
"The sentence is not nearly long enough and we disown her after what she's done."
Mick Philpott, Mairead's husband is still in jail after he was found guilty of manslaughter and given a life sentence with minimum parole of 15 years' imprisonment.
Mick had first come to prominence in the British media as a result of his large family (having fathered 17 children by various women) and his reliance on state benefits.
On May 11, 2012, the Philpott home was seriously damaged by fire around 4am.
Five of his children, who were asleep upstairs, all died at the scene, while their half-brother died two days later.
The Philpotts held an emotional news conference, in which they purported to describe the events concerning the fire and plead for help.
Later, police stated that petrol had been found inside the letterbox to the Philpott residence, thus sparking a murder investigation.