You're trying to replace his income.
$2 million earning 4% gives an income of $80,000.
If she's young with a small family, she may be able to return to the workforce in a few years perhaps getting training or college first.
If she's in her 40's with a houseful of kids, that's not a realistic expectation for a while. In the meantime there's tuition, camp, weddings, etc.
(That's where the 'askanim' come in and tie up the LI in annuities for the weddings and go public with tzedoko campaigns.
The couple should know how much he's insured for and how that money will be used to care for the family. Or at minimum, which financially savvy friend or relative they can rely on for advice.)