A grieving daughter showed up to her late mother’s open-casket viewing in South Carolina to say her goodbyes, but instead found someone else in the coffin — wearing her mom’s “Sunday best,” a shocking lawsuit claims.

Iris Gordon signed a $13,820 contract with Ocean View Funeral Home for a wake and graveside service after her 87-year-old mother, Iris Evans died in January, only to be shocked by what she saw when she went to pay her respects, according to a lawsuit filed Thursday in Horry County that was obtained by The Post.

Before the scheduled viewing, Gordon gave Atu Williams, one of the funeral home owners, her mother’s black-and-gold African attire, scarf, hat, wig and undergarments, court papers said.

“For her family members, these items were provided with an intent to create a long-lasting final image of Mrs. Evans — reminiscent of her dressed in her Sunday best while singing in the church choir,” the lawsuit claimed.

Evans was a devout Christian great-grandmother who loved music and attending church.

Gordon and more than 20 of Evans’ family members arrived for the open-casket viewing on Jan. 30, according to court papers.

But after the grieving family approached her casket, they shockingly discovered the body lying inside was an “unknown stranger in Mrs. Evans black and gold attire, scarf, hat, and wig.”

“Iris was devastated by what she saw and the experience,” the lawsuit said.

“The image of an unknown stranger dressed as her mother at the solemn occasion of a viewing in front of herself and all of her closest family members caused her humiliation, embarrassment, and to break down emotionally.”

Gordon immediately contacted Ocean View Staff and Williams, who allegedly acknowledged the funeral home had made the disturbing error.

A new open-casket viewing was scheduled for two hours later. When the family returned to the funeral home they found Evans in the casket “dressed in the same clothing previously worn by the stranger,” court papers said.

The stranger whose body was found inside the casket was not identified in the complaint, and Gordon’s attorney, Benjamin Baroody, did not immediately respond to The Post’s request for further details.

Gordon claims to have suffered “emotional distress … post-traumatic stress disorder, anxiety, depression” — and is seeking the cost of the services, $13,820, plus additional unspecified damages, court papers said.

Ocean View did not immediately respond to The Post’s request for comment.