Colin's elderly sister was at his bedside for his final hours, Henderson said. He died on Wednesday evening.
"I'm at home in LA consoling two children who are struggling to understand why they are unable to see grandad," she said.
"It's gut wrenching to watch your kids say goodbye over FaceTime with tears rolling down their cheeks."
Her father had urgent open heart surgery last Thursday to repair two leaky heart valves.
While the operation went well, on Tuesday Rachel got a call to say her father was back in ICU with a suspected bleed and had been put on life support.
She immediately called the NZ Embassy, who advised she could travel here but would have to be quarantined for two weeks before she could see her dad. They put her in contact with the Ministry of Foreign Affairs and Trade, who sent her an exemption form to fill out.
Henderson earlier told the Herald that while she supported the Prime Minister's approach to the Covid-19 pandemic, she was angry and frustrated that there's been no room to move in unique situations like hers.
The Government's strict quarantine rules have come under this fire this week, after it was revealed that of 24 people in quarantine who asked to leave early to see dying relatives, not one was allowed out.
On Friday, a High Court judge overruled Oliver Christiansen's lockdown order so that he could be at home with his dying father.
The Prime Minister has since ordered a review of all 24 cases, with findings due by the end of the week.
Another heartbroken daughter told the Herald she believed her dad's life was cut short after having no family support when he was dying in hospital.
Ken Barker was brought home to die of cancer with his family around him after Palmerston North Hospital refused to allow his children to visit him there.
"It was absolutely disgusting my dad was left alone in hospital for 10 days when he was dying," she said.
Rachel Henderson - now trying to come home for a funeral rather than to say goodbye - hoped that sharing her story would help others caught in such a "horrible situation" and lead to change.
She said she was "so very grateful" to the staff at Christchurch Hospital, who did all they could for her father.