Digital marketing is a better option as social media marketing is a branch of digital marketing itself, while learning about digital marketing you get to learn about social media marketing, blogging ,seo and many other things.
Do digital marketing is better. I have also done it, it opens more opportunities. And more internship also. Social media marketing and SEO and other all come under this only. You will get a brief idea about everything.
Digital Marketing is better because all types of marketing courses are included under this, including Social Media Marketing. And having knowledge about different types of marketing will add a different perspective thereby increasing your skills.