A daughter screamed at her elderly mother to get in the car and flee the February 7 bushfires in a harrowing last telephone call, the Victorian Bushfires Royal Commission has heard.

But Faye Walker, 80, her husband William, 85, and their disabled son Geoffrey, 53, died in their home at Narbethong, near Marysville.

Their Toyota sedan was found two days later parked at the entrance to the house, unlocked and with the keys inside.

A laptop, handbag and medication were packed in the vehicle.

Although the car had only minor damage from the fire which obliterated the house, the family's pets were found dead inside the sedan.

Forensic teams concluded the family intended to escape in the car but were blocked by a fallen tree on the driveway.

One of the Walkers' three daughters, Vivian Creek, said that when she spoke to her mother on the telephone about 5.15pm (AEST) on February 7, Faye Walker sounded terrified as the power went out and she described seeing flames in trees nearby.

"I screamed at her to get in the car," Ms Creek said in a statement, read to the commission.

"I hung up the phone and I didn't hear from her (again)."

Another daughter, Julie, spoke to her mother about the same time and told the family to get out.

"I said, 'Mum get in the car and get out of there,'" her statement said.

"I said, 'Don't worry about anything just get in the car and go,'".

A neighbour described hearing an explosion at the house about 5.45pm.

The three daughters, Vivian, Julie and Marilyn, learned two days later that their parents and brother had not survived the inferno.

Two of their husbands had travelled through a roadblock in a desperate search for their in-laws and made the grisly find at the Narbethong property.

The daughters, waiting at the roadblock outside Healesville on February 9, were inconsolable when the news was broken to them.

The commission also heard a couple, whose names were suppressed, died in their home near Marysville, despite a sprinkler system spraying water over the house as the fire raced towards them.

The royal commission on Wednesday began examining the deaths of 40 people who died as a result of the Murrindindi fire, which swept through Narbethong and Marysville.