Bobbi Kristina's Grandma Mentally Prepared For Her Death

Whitney Houston's mother is mentally prepared for her granddaughter Bobbi Kristina's death ... because she says it's God's will.

Cissy Houston went on "Midday's With Shaila" on WBLS in NY and thanked everyone for praying for Bobbi Kristina -- but also revealed she's finally at peace with whatever happens.

She said, "If He works a miracle, thank God. And if it happens the other way, I'm alright."

Bobbi was moved to a rehabilitation facility in Atlanta .. where she can get long term care.