I am not sure if i can write 'him/her' or 'himself/herself in an essay.
It's a bad habit to get into. The pronouns "he," "him," and "himself" are still the grammatically correct singular form here, but, as Simone will no doubt vocally protest, can be read as sexist use of language by those ignorant of the etymology of the words and of the nature of gender in language. A compromise is to simply go with the plural form, so that you can correctly use plural pronouns. So,
Compared to their peers who study in their home countries,
students who
are living overseas will be more successful in adapting
themselves to new environments and situations in life.