She is serving a "life sentence" of heartache after her son, Joshua DiPietro, was shot in the head on Victoria's Mornington Peninsula on Father's Day in 2017.

The 31-year-old was gunned down in a car at Rosebud and died in hospital a day later.

Craig Williams has admitted to Mr DiPietro's manslaughter and his co-offender John Godfrey to recklessly endangering serious injury.

Their mother, Tracey Godfrey, admits to helping her sons avoid justice by removing CCTV footage and ammunition from the scene of the crime.

Mr DiPietro's mother says what was meant to be a family day turned into "the most horrific day of our lives".

"I will never be able to tell my son 'I love you'. I will never be able to speak to him or hold him again," Mrs DiPietro told the Supreme Court of Victoria on Monday.

The coronavirus pandemic meant she addressed Tracey Godfrey via video link instead of in person after the woman pleaded guilty to assisting her sons avoid apprehension.

"One of the most valued and treasured gifts ever given to me was the life of my son, Josh," Mrs DiPietro said.

"We have been given a life sentence.

"We feel like we have had everything taken from us. Our grief never stops."

Tracey Godfrey's lawyer asked for the 50-year-old to be fined or handed an adjourned undertaking, which mandates she comply with certain conditions, as punishment for her crime.

The woman was well aware of the devastation wrought on Mr DiPietro's family and wishes with all her heart it hadn't happened, barrister Samantha Poulter said.

Prosecutors have not pushed for Tracey Godfrey to be jailed.

She remains on bail and will be sentenced at a later date.

Her sons are expected to face a plea hearing on June 1.

Tracey Godfrey's ex-partner, David Lyons, was last year jailed for at least 20 months for his role in the fatal shooting, including removing a bullet cartridge from the scene and intimidating a witness.

Australian Associated Press