In a plea forwarded through the Harijan Sewak Sangh, the mother alleged that convict Vinay Sharma has been deliberately trying avoid to death sentence and "dissemination of justice".
"The mercy petition filed by one of the convicts namely Vinay Sharma... out of three, deliberately tries to avoid the execution of death sentence and hamper the dissemination of justice," she said in the plea.
"It is therefore most respectfully prayed that the said mercy petition is liable to be rejected," the plea added.
On Sunday, the Delhi government "strongly recommended" the rejection of Sharma's mercy petition. In the recommendation, Delhi Home Minister Satyendar Jain said this was the case where exemplary punishment should be given to deter others from committing such atrocious crimes.
The petition was forward to the city government after the Supreme Court and the Delhi High Court rejected it, saying Sharma "does not deserve any mercy".
The 23-year-old woman was gang raped and tortured on December 16, 2012, which led to her death. All the six accused were arrested and charged with sexual assault and murder. One of the accused was a minor and appeared before a juvenile justice court, while another accused committed suicide in Tihar Jail.
The four convicts were sentenced to death by a trial court in September 2013, and the verdict confirmed by the Delhi High Court in March 2014 and upheld by the Supreme Court in May 2017, which also dismissed their review petition in July 2018.
( With inputs from IANS )