i would like to make website about home remedies but my question is which is better to make a website about home remedies as whole or to make web site for special topic like for example home remedies for cough
I like your idea about making a website for home remedies. It doesn't have to be focused on just one home remedy. Having multiple pages on different home remedies to different ailments will allow you to rank for lots of keywords, some easier than others, and it gives your site value and gravity with Google. If you backlink well to each page then you can get traffic for a whole lot of different keywords to your site. Once they are at your site they might find something else of interest as well.
I would prefer to build a website for home remedies in general and then you can have sub categories depending on what type of home remedy such as home remedy for cough, arthritis, headache etc. It will be easier for you to rank in google based on SEO in that case. just make sure you use proper keywords and optimize them.