Lila Marmont was seven months old when she succumbed to the effects of an undiagnosed white cell disease at home yesterday.

Doctors detected a medical condition affecting Lila's brain when she was 10 weeks old.

She had been in and out of hospital since, but doctors had never given a definitive diagnosis, Lila's grandmother, Sharon Marmont said.

"It's very hard for all of us because we had her for such a short time," Mrs Marmont said.

"Nobody could give her a time frame for how long we would have with her - we were just day to day with her.

"She was an absolute angel, a beautiful little girl."

Doctors inserted a feeding tube into Lila's stomach last week when her health waned.

Jay Marmont all but abandoned his training in the week leading to round three of Super X in Perth last Saturday to be with Lila and Abby.

He turned in a third-place finish despite the trying personal circumstances and later said his baby was an inspiration.

"My daughter ... she's a fighter and she's a battler and she definitely gives me inspiration and makes me go out there on the weekend and want to do it for her as well," he said.

Lila's funeral will be held on Monday.

It is not known if Marmont will compete in round four of the Australasian Supercross Championship in Canberra tomorrow.