There are several citation styles and also, within one style, the way of composing the works cited list may vary (depends on the region, country, editors, etc.). But going by the standard, I would say that:
1. correct is c) - Underline or italicize the titles of books and periodicals.
2. correct are a) and b) - A writer should always list a direct source (address of a portal or direct link) and, in most of the cases, the date when the content was accessed. Answer b) sometimes is not necessary, but is definitely useful, because the websites change often and we cannot provide the hard copy of the text.
3. Each time when you cite a source in the text of your paper you need to add 1) the author's surname and 2) the page number of cited/quoted text. Both information are related to the full description of the quoted text in the works citied list, with the title, year and place of publishing, publisher, etc. The surname allows to identify the work of the author, and the page number - to locate the quotation within the source.
Hope it helps!