Feasibility of converting all python pandas/numpy code to base python
I'm only going to address the 2nd point. Reimplementing all of numpy/pandas is certainly a very large and useless task. But you're not reimplementing all of it, you only need some parts, and if it's only a few functions, than it's certainly possible.
I'd start from a working script, replace arrays by python lists, and implement the needed fucntions one by one. For SO specifically, I suspect you're better off asking specific questions, e.g. how to implement an analog of a function X in pure python etc.
General python question- 
I have built a script using numpy and pandas libraries. I have now been told that I cannot use any libraries- only base python to code. This is because apparently open source libraries are not approved. 

Does this restriction make sense? Isn't base python as open source as pandas/numpy libraries are?
Is it possible to convert pandas/numpy code to base python? Does this sound like a simple exercise or does it require learning a lot of new functions? Majority of the code is reading tables and then using if/then type statements and looking up values from other tables to generate and populate new tables.