If a website has few images and one or two videos, do I need to include them in the sitemap or have a sitemap separately for them?
As others have stated, a sitemap isn't necessary for such a small amount of content. If you really want to have one, then including everything on one sitemap is okay.
Can you combine an XML Sitemap with an Image XML Sitemap?
Can you combine an XML Sitemap with a Video XML Sitemap?
<?xml version="1.0" encoding="UTF-8"?> <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:image="http://www.google.com/schemas/sitemap-image/1.1" xmlns:video="http://www.google.com/schemas/sitemap-video/1.1"> <url> <loc>http://www.example.com/videos/some_landing_page_with_video_and_images.html</loc> <image:image> <image:loc>http://www.example.com/image.jpg</image:loc> </image:image> <image:image> <image:loc>http://www.example.com/photo.jpg</image:loc> </image:image> <video:video> <video:thumbnail_loc>http://www.example.com/thumbs/123.jpg</video:thumbnail_loc> <video:title>Grilling steaks for summer</video:title> <video:description>Alkis shows you how to get perfectly done steaks every time</video:description> <video:content_loc>http://streamserver.example.com/video123.mp4</video:content_loc> <video:player_loc>http://www.example.com/videoplayer.php?video=123</video:player_loc> </video:video> </url> </urlset>
If your site uses a lot of graphics that are central part of your business strategy, I'd recommend you use one.
If it's just a few images / videos, perhaps skip the use of sitemaps as Google will take care of it.
Here's an excerpt from https://support.google.com/webmasters/answer/178636?hl=en
Same goes for the videos as well but be sure to follow the guidelines mentioned here: