Sorry for asking homework, but this question is really confusing; I think the answer is some type of cousin, but I don't know if it's first, second, third, etc. and once removed, twice removed, etc.
I have simplified and rephrased the question below:
Your brother has died and left his wife widowed. Your maternal aunt has also died and left her husband widowed. If the widow and the widower marry and have children then what is the relationship of those children to you?
(The state of homework these days...)