Upon his return from the battle, Bilbo comes back with two little treasure chests, one filled with silver and the other one with gold, and says "<span>That will be quite as much as I can manage". Taking this into consideration, we can conclude that your best answer is option A.</span>
A: Mom and her sisters have decided to go on a trip together
for B it should be: His uncles and my brother were going on a camping trip
for C: the wording is just funky.
for D it should be: Both Natalia and Mike have invited us over
Hopefully this helps and good luck.
I am not sorry if I will be correct but I think it is D ..