Python giving memory error while fitting the text into vector using various vectorizer
to answer that question you need to get and give us more information, no chance to advise without knowing where the OOM is thrown and how the memory profile looks like. You may tune the memory usage of your program also in other parts than the part where the error came from, to raise the limit.

Just one hint for a cause that can be resolved without getting more physical memory: 
Sometimes you can "lazy load" large data sources. Get it record by record or chunk by chunk, then process it, and write results to the sink, before you get the next record into memory. This is done with python generators, watch out for the keyword "yield" that is used instead of return. 
https://stackoverflow.com/questions/1756096/understanding-generators-in-python

further you may be better off using low level libraries for certain tasks, see i.e. http://www.nltk.org/book/ch06.html  2.4