I am not going to speculate on this particular accident but wait for the report, in the meantime obviously it is a sad loss for all of those involved personally.
As to the single/twin one pilot or two debates all I will say is that it is possible to fly singles at night with one pilot perfectly safely. It has been done the world over for years, it does however have an increased risk of incidents due to certain factors. As time and technology move on we reassess our risks and sometimes change how we do things.
It was mentioned here that British police operate single pilot at night in twins and not IFR. Some are in fact IFR but most are not, but ..............the aircraft are equipped for IFR.
Spatial disorientation has killed many at night and I have lost friends who drove twins in to the deck from black hole syndrome without ever entering a cloud. The difference a newer more modern airframe could have over an aged jet-ranger is the full auto pilot suite. Once you become disorientated or inadvertently enter cloud you engage the autopilot and let the computers keep you alive while you manage a recovery to a suitable airfield with a coupled ILS if required. Training to do this is carried out regularly.
It will not save you in every situation and in fact humans being what we are some will push the limits using the kit they are not licensed to and get themselves into trouble not out of it. There is no one solution to all problems and always exceptions to the rule. We however need to try as hard as we can to prevent the major reasons not use the exceptions and previous practices to justify continued risky operations.
I fly a 1969 "A" conversion jet-ranger which has had nearly every part rebuilt or replaced over the years and it is still a beautiful smooth craft to fly. I have flown it at night in years gone by but am older and wiser now and would not do so again. I also fly a slightly newer jet-ranger with basic autopilot. I would prefer to fly this at night as the automation should I become spatially lost could save my life. It is still single pilot single engine but an improvement over the older cab. I can also fly a fully IFR certified 135 with two engines, again given the choice I would prefer to travel in this over the other two. It offers me the autopilot as the newer jet-ranger but now with the added ability to fly coupled approaches if I am really in the brown stuff. Added to this it has the redundancy of two engines.
Given the choice business will try to cut costs and there is a balance to be found as in the real world budgets are not limitless. We as the pilots need to try and make our employers and passengers aware of the risks and benefits of certain operational practices so that an acceptable balance can be found. This is not an easy task.
As the saying goes, if you think safety is expensive you should try an accident!!