Ms Clarke's father Lloyd and brother Nat on Sunday evening addressed the crowd who turned out to support the Clarke family and friends following one of Queensland's worst cases of domestic violence.
Ms Clarke and her children Laianah, Aaliyah and Trey were killed at the hands of Rowan Baxter.
Baxter set alight the car his children and former partner were in while Hannah was doing the morning school run on Wednesday.
During Sunday's vigil, Ms Clarke's father praised the community for supporting his family.
"This has been the worst week of our lives," he said.
"We would have felt lost without all your support.
"I don't know how we can repay such kindness."
Many who addressed the crowd spoke of Hannah's courage and love.
Queensland Police Commissioner Katarina Carroll said Hannah was able to give a detailed account of the attack while fighting for her life.
For Ms Clarke's long-time friend Nikki Brooks, the grief she felt led to a call for action against domestic violence.
She called for the community to not turn a blind eye.
"We are a nation in pain," she said.
"Don't back away from your friends for the sake of convenience.
"Time's up on domestic violence."
