When a Mafia leader goes to jail, his impulsive shopaholic housewife must assume the role of mafia boss and finish his last deadly mission without jeopardize the rest of the family.

I’m hooked on the premise.

But:
“finish his last deadly mission without jeopardize the rest of the family.”

If there’s no jeopardy, there’s no 2nd and 3rd Act. There has to be jeopardy. Indeed, it’s because of jeopardy to the rest of her family (and herself) that she must take over.

Also, about “last deadly mission”

Since when did a mafia Don ever have one last deadly mission? They can never retire or transition out of the family business. That’s part of their existential dilemma. Ask Michael Corleone.

Better.

But wouldn’t it also be likely that her husband’s incarceration creates immediate jeopardy in the form of rivals taking advantage of the situation to divide up his turf and take down his family?

(Again, the Godfather has become the golden template for the gangster genre. Even though yours is a comedy. It is a comedy, right?)

Well, the jeopardy is there, so why not?

I don’t know what your idea of the big job she has to finish for the family. But it wouldn’t hurt if it has something to do with taking down his arch rival. And then the husband goes to jail(complication triggering greater jeopardy…) and now she has to do the job before the arch rival, sensing vulnerability and opportunity, closes in for the kill shot.

Anyway, your premise generates all kinds of comedic choices. IMHO you’ve got a premise with an genuine hook.