"I give it to God one time because I know he's able," she told New York radio station WBLS-FM (107.5) on Wednesday. "And I cannot change a thing."
Her 21-year-old granddaughter is "the same," said the soul and gospel singer, 81. "You know, still not a great deal of hope. We're praying."
Bobbi Kristina was recently moved from Atlanta's Emory University Hospital to a rehab facility better equipped to handle long-term care, it was reported Friday. Whitney Houston's only child with Bobby Brown was found unresponsive in a bathtub on Jan. 31 at the home she shares with Nick Gordon.
Gordon, who hasn't been allowed to see her since she was hospitalized in a medically induced coma, went into rehab after a dramatic, intoxicated taped appearance broadcast on the March 11 episode of "The Dr. Phil Show"
The 25-year-old admitted to Phil McGraw that he'd been drinking heavily and using Xanax.
Bobby Brown and other family members had been at Brown's bedside when she was at the hospital.
Doctors have tried bringing "Krissy," as the family calls her, out of the coma more than once, but were unsuccessful after she began to suffer seizures when the sedating medication was reduced.
Said Cissy Houston, "I'm asking everybody, just pray to the Lord who we know can do something about it. If he works a miracle, thank God. If it happens the other way, I'm all right."
Meanwhile, in other Brown family drama, cousin Jerod Brown -- who had been speaking to the press about Krissy's condition and was denounced by Bobby Brown's lawyer as knowing nothing directly -- was arrested Monday in Atlanta, according to Us Weekly.
Police said they smelled marijuana coming from Jerod Brown's car while they were driving behind him, Us reported, and pulled him over. He was arrested on an outstanding warrant as well as on suspicion of driving without a license and giving false identification to the police.