When Devyn Johnson unexpectedly lost her mom, Shannan Lee Phillips, on June 2, 2017, in Washington state at the age of 41, it wasn't until six months later that Johnson was able to sit in her grief and mourn her mother.

As the eldest, Johnson said a lot of the financial responsibility of planning the funeral fell on her. She was 25 years old.

"I hadn't lost anyone before," she said. "I was just like, 'Now what?' And instead of being able to be sad and grieve, I had to go into business mode, put my feelings aside."

Johnson, now 29, said there can be so many unanticipated costs associated w...