My default answer would go with an ASEL. For a family-transport mission of a few hundred miles there are only a few circumstances which would justify the numerous drawbacks of a twin...

The need to fly long legs over water, or mountainous terrain under night / IMC, would justify a twin in my mind. Bu unless there is water involved, you could save a bunch of money and risk by sticking to to day VFR, especially with the familia on board.

Twins drawbacks relative to ASEL ...
Double+ Mx costs.
Double Fuel Costs.
More than Double+ insurance costs for most non-pro pilots.
Significant operational risk unless the pilots stays VERY proficient with single engine ops.
More things to break...reduced dispatch reliability.

Most non-pro pilots are safer doing a day VFR off-airport landing in an ASEL than dealing with a Vmc cut in a loaded-up twin.