The father of two young girls who helplessly watched their social-worker mother gunned down in The Bronx said their grandmother has “absconded” with the kids and has launched a fight for custody.

Clarence White, 37, said he hasn’t spoken to his daughters since his ex-girlfriend, Lakisha Scriven, 30, was shot in the head and killed as she strapped Alanna, 8, and Aleila, 5, into her Ford Explorer on Dec. 7 on a street in Wakefield.

Scriven’s mother, Marcia Scriven of Rosedale, Queens, illegally “absconded” with the girls, according to White’s attorney, Steven Gildin, who filed papers seeking custody yesterday in Queens Family Court.

“His rights as a father have been completely trampled on,” said Gildin. “We want the kids back where they belong; with their father for Christmas.”

Marcia Scriven hung up on a Post reporter, and her attorney did not return a message.