The mother of a man who attacked an armed guard at Victoria's parliament house before taking his own life has asked why police did nothing despite a warning her son was acting suspiciously.

The 30-year-old mentally ill man approached the protective services officer (PSO) on the steps of parliament on December 11 and asked him for directions before attacking the guard with a hammer, striking him to the head and body.

David Hollingsworth, of Chadstone, then took the officer's gun and fled before shooting himself on nearby Wellington Parade.

The incident, at 8.30pm, came six hours after a woman had reported Mr Hollingsworth to a PSO after she saw him acting "in a peculiar manner".

At a directions hearing for an inquest into his death on Tuesday, his mother Josie Hollingsworth had several questions for Deputy State Coroner Iain West, including why only one PSO had been stationed at parliament house that night.

She wanted to know why police failed to act, despite a report that her son had been acting suspiciously.

It was fortunate that he did not kill someone, she said.

"What were the police doing from two to eight (pm)?" she asked.

"It could have been a catastrophe if David had a bomb in his bag."

Mrs Hollingsworth slammed the media coverage of the incident, saying it had caused her great distress as she tried to cope with her son's death while battling cancer.

She said images of her son's body were shown on television and reporters had been to her house.

"I'm going to attack them (the media) if they come to say the wrong things," she told the Victorian Coroners Court.

"I'm very, very upset. I will not be the type of person who lets people dirty my son.

"You see on the plasma TV the whole body of your son.

"I can't sleep, I can't do nothing, I can just see the face of my son."

Mr West told Mrs Hollingsworth that he did not have the authority to direct the media on what to publish.

PSO James Vongvixay suffered a fractured skull and bleeding on the brain in the attack.

He was released from the Epworth Rehabilitation Hospital on Friday.

* Readers seeking support and information about suicide prevention can contact Lifeline on 13 11 14 or Suicide Call Back Service on 1300 659 467.