The correct option is C heading
Option C, 'heading' is the most apt option that fits in italicized word of both the sentences. Heading as a verb means going towards somewhere. It is also used for the title of a paragraph or book. Sentence I means that Saurabh was heading towards the library when he met me. Sentence II means the newspapers carried the news about the murder with a large heading. Option A 'starting' means to begin. Option B 'venturing' means to do something risky or to volunteer. Option D 'prefixing' means adding something in the beginning. Thus, A, B and D would not fit both the sentences together and correct option is Option C, heading.