53-year-old Mary Rose Ballocanag, of Teaneck, N.J., was being treated at Christiana Hospital following the July 6 crash on Route1 in Townsend, Del.
The van she and her family members were riding in was struck by a pickup truck that had swerved out of the southbound lanes and went across the grassy median.
The victims, 61-year-old Audie Trinidad, 20-year-old Kaitlyn, 17-year-old Danna, and 13-year-old twins Melissa and Allison were pronounced dead at the scene.
The girls were not wearing seatbelts, police said.
The pickup truck, driven by 44-year-old Alvin Hubbard of East New Market, Maryland, also hit a car driven by 24-year-old Brian Kern of Bethlehem, Pa. Both Hubbard and Kern survived, as did a passenger in Hubbard's truck.
So far, no charges have been filed in connection with this crash.
In an interview with Action News, Kern said the crash scene looked like a "war scene."
"Out of the corner of my left eye, I see this F-350 truck wildly swerving in the median through the grass, and I knew it was coming right for us," Kern said.
DelDOT says it will install cable barriers on Route 1 between Odessa and Smyrna to prevent future wrong-way crashes.