Can I include other students' master thesis in the literature review of my master thesis? These master thesis that I found are published in Google Scholar and other online libraries/archives.
Actually, it might be essential to do so. Especially if you draw on or extend their work. You need to cite anything you use, of course.
Moreover, a literature review, if it is to be complete may need to draw on things that are "visible" even if not formally published. You may, however, need to make it clear that some such things haven't been peer reviewed so the reader needs to take some caution in accepting their results.
If the thesis is relevant, then yes, you can certainly include it. If the thesis disseminates important and original findings on the topic you are surveying, then you should definitely include it.
I once read a peer-reviewed book-chapter by a professor that cited a master's thesis (the thesis was neither by the professor himself nor by a superstar).