Prop job .... let it make it simple for you
B1900 have two engines, unless there is a catasthophic failure, they continue flying. If well maintained B1900's don't fall out of the sky.
IF rated Pilots, should know about Grid MORA, ( cumulo granite not good that's why there is Grid Mora)
WX bad in Bukavu, no Approved approach in Bukavu - wihout VMC conditions.... go to alternate and wait it out.
Insurance investigators will probably check maintenance records to see whether there were any oustanding MEL's .... sorry what am I thinking pilots in Africa don't write up defects, then when it bites them in the ass everybody says what great guys they were and how they are so professional and how they don't take any cr.p from their employers.
Prop Job at a tender age of 23 let this be a lesson for you ... nobody forces you to fly, and aircraft just don't fly into the ground or drop out of the sky. You as PIC are accountable and have to set a good example for your SIC. There are legal ramifications, it is a pity they don't teach or emphasis this with airlaw.