Minimum table dimension in thesis
TBH, I never heard of such a minimum for rows, columns or cells for a thesis. I suppose it would be same for any other table.

If you really believe that the table doesn't look so neat with only a few columns for too many rows, then transposing the table would be a good idea (as @Wrzlprmft suggested). If the amount of data looks unworthy of being depicted as a table, then you may you any other sort of graphical presentation such as a chart. This might help you with more innovative ideas for presentation.

Having said the above, this really is a question for your thesis advisor and would depend on any guidelines referred by your institution on writing a thesis.