Bobbi Kristina, 18, disappeared after the funeral while friends and family convened at a restaurant in Newark, New Jersey, to remember the 48-year-old pop legend.

One friend of the family said: “Everyone was freaking out and calling Bobbi Kristina’s cell. It was so much commotion and activity after the funeral that Bobbi Kristina just slipped away. Ms. Cissy [Houston, Whitney’s mother] was beside herself.”

The source added: “Cissy and others won’t admit out loud that Bobbi Kristina has a drug problem. But they know it and have been trying to keep her straight even before Whitney passed.

“But losing your mother and the life you’re accustomed to all in one day is enough to send anybody off the deep end.”

The source also said: “It’s a horrible situation for everybody. They tried to save Whitney, and it didn’t work. Now with Bobbi Kristina, they fear the same thing is happening again and they wont’ be able to stop it either.

“Bobbi Kristina is all Ms. Cissy has left of Whitney. She’s so tired, but she’s ready to fight again to save her grandbaby.”

Multiple sources close to the family say they had serious discussions over whether to send Bobbi Kristina to rehab.

She has already checked into a rehab facility for a drug problem last year.

A Houston family spokesman said later: “There was some confusion about Bobbi Kristina’s whereabouts last night for a short time, but she’s OK.

“She needed some time alone. She is going through a very hard time as you can expect.”

The spokesman and Bobbi Kristina’s father have both denied that she has taken drugs.

Denise Council who attended the ceremony at New Hope Baptist Church on Saturday said: “Bobbi Kristina broke down, but she was good. She was up in the front row…and [did] pretty good, all considering.”

Whitney Houston was buried in her hometown, Newark, New Jersey, at the weekend, following her death on February 11.