I think perhaps the daughter(s) were threatened by dad's new relationship and wanted to stop the new bride from accessing dad's money, which they perceived as being their "due" upon his passing.
The only thing that puzzles me is why not leave a body to be found. But in this particular case, maybe they needed there not to be. Give them time to go through the courts and declare him dead, meanwhile allowing time for their attorneys to thwart any attempts to inherit by their new stepmom.
SBM
I think Gitana may have provided the answer as to why disappear Bob rather than leave his body to be found.
Gitana provided links to several articles, going back as far as 2005, outlining the extremely lax (to put it kindly) performance of the courts in overseeing conservators.
Under normal circumstances, an 81 year old man found dead at home would be assumed to be death via natural causes, so long as there were no overt evidence of violence. There wouldn't even be an autopsy, if it looked as though he died in his sleep (for example). The number of autopsies done has dropped steadily since the 1970s and it's now done in less than 10% of all deaths.
However, the next of kin can always request an autopsy. And with Bob's marriage, his next of kin was no longer his eldest daughter, it was his wife, Fontelle.
Uh oh. They could not be certain that Fontelle would just accept that Bob had died of natural causes, could they?
If the medical examiner ruled the death was homicide (death caused by another human being), that could tie Bob's estate up for a long, long time. No conservatorship would be assigned.
However, if someone happened to read the series in the
Los Angeles Times that Gitana cited or decided to do a little research when s/he felt financially threatened by an unexpected December marriage, then it would be clear that getting a conservatorship would be, in many ways, just as good as inheriting outright.
No, the estate couldn't be divided up and the heirs would not have that large bulk sum each to spend but a conservatorship could maintain or even improve the status quo.
There were lots of good reasons for Bob to disappear versus for Bob to be found by his housekeeper seemingly dead of natural causes.
Personally, I think the housekeeper's appearance that day was an unpleasant surprise. I think the plan was for her to come on Tuesday, her usual day, and notify the family that Bob was missing. No need for JeM to have to provide any alibi at all because no one would have known he was there the previous day.
It's a theory.