There’s always the option of burial in a piano case (see link). Arrangements could be a graveside service, no pall bearers needed, just a crane. Not sure where they’d get a vault that big - most cemeteries require them. She did weigh a lot less than this guy (1041).
Benville, Illinois: Grave of Robert Earl Hughes, World’s Heaviest Man
https://www.roadsideamerica.com/tip/3877
OMG! It’s incredible what extremes the human body can be pushed to, and still with keeping that person alive, if not fully functioning.