What Math is used in Development Economics? I would like to ask what kind of math is used in Development Economics?  

I have one more semester in my Master of Math programme before hopefully entering a PhD in Economics and am considering specializing in this; so I would like to know what I should take or review next semester.  Are the topics listed on the wiki-page for Mathematical Economics applicable?  Being differential equations, linear algebra, optimization, and analysis.  Or would statistics or data science be more applicable?  

Thank you
This does depend on whether you're looking to do applied econometric work, in which case statistics is definitely the way to go or something theoretical, in which case a good understanding in the maths you listed will go a long way. Of course it's always better if you understand both - since you're doing a master's in math, you should already be quite fluent with the math required, so I'd go with econometrics.

There's a growing amount of literature available, but if you have time to spare, I'd give the topics in Nafziger's "Economic Development" a glance: http://tabesh.edu.af/Books/economic/Economic%20Development.pdf