Grandparents who pushed their two-year-old grandson out of the way before they were mowed down by a car have been praised for their final act of love.

Vicky's parents were struck by a Toyota Yaris while walking along a footpath in Wantirna South, in Melbourne's east, about 12.20pm on Thursday, July 10.

They were on their usual walk home from a playground at Coleman Road Reserve with Vicky's toddler son, their grandson, in tow.

The grandmother, 59, died at the scene. The grandfather, 60, was rushed to hospital in critical condition and died two days later from a traumatic brain injury.

Miraculously, their grandson survived. He was found near the scene of the crash by a neighbour, Tracey Jean, with only scratches to his face.