Well, I wonder if the sale was a great opportunity, but the rush was about killing Liz before she and Sergio would depart for the anniversary trip.
If so, why could it matter? What happens when people are on an anniversary vacation? One though is obvious. A young couple, 5 years together, vacation, she is close to 30, the perfect situation for, say, family planning. And if they, indeed, return pregnant, and the person is vested into killing Liz, it would be a different kind of killing in the state of TX.
(I am not thinking this is what the Bs were thinking of, but it is what often happens, and hence, it could explain the fear and the haste of the killer).
Otherwise, why else could it be important to do it before their 5-year anniversary? What changes after 5 years of marriage? Any ideas?