Do all Elsevier journals require ONE column format for manuscripts to be reviewed? I want to submit my paper to Elsevier Optics Communications, but I'm confused about the template of the journal. According to the guide for author, the manuscript can be in either Word or LaTex format. 

It seems that there is no sample template for Word format, but they DO say that the Word template should be in ONE column. 

This journal doesn't provide its own LaTex template but they provide the general template for all types journal in Elsevier. There is also a sample LaTex template which is in ONE column format. There are several options including "preprint", "review", "1p", "3p", and "5p". The default option in the sample template is "review" which has ONE column format. 

What makes me confused is that the final format of Optics Communication (as can be seen in published paper) is TWO column. Does this journal (and maybe all Elsevier journals) require ONE column format for the manuscript to be reviewed?
 After the manuscript is accepted, the officer of the journal will turn the manuscript into TWO column.
In mathematics, usually authors aren't expected to format their paper according to the journal's template until after the paper is accepted. Even then, authors usually don't bother and leave it up to copyeditors. This is the case for Elsevier as well as other publishers. Although publishers' websites often "encourage" authors to format submissions in a certain way, these suggestions are typically ignored.

What is true for math might not be true for optics, so it is probably worthwhile to ask a scientist with firsthand knowledge of the journal (or at least the research field in general). Perhaps such a person will answer your question here. Otherwise, I would suggest that you only invest any effort into reformatting your paper if such a scientist (not an Elsevier employee) confirms that this is indeed important. If it's not practical to ask a colleague, you might e-mail a member of the journal's editorial board with this question.