I agree with all the recommendations for other places, especially the ferry trips. However, if you really want to limit yourself to Emeryville, there is a great multi-use path along the waterfront.
Emery-Go-Round out to the Emeryville Marina would be a good start, then from the fishing pier maybe walk the trail to the Berkeley pier, and catch a Cap Corridor train back to Emeryville. Or tackle a shorter or longer stretch, or head toward the Bay Bridge. Look for information about the San Francisco Bay Trail, there is a lot more out there besides the
official site. There are also some local food shacks along the trail, haven't eaten at any to know how good they are, google maps seems to be the best place to find what to research. There are some benches and tables in some spots in case you would rather picnic. There are some really incredible views from that section of the trail but dress in layers for cold.
I've always felt safe on the trail during daylight and dusk. If your train schedule allows for it (and it isn't foggy), you want to be on the waterfront with a clear view of the Golden Gate for sunset. With some research and determination (and weather luck}, you can determine exactly where to be to see the sun sink into the water under the bridge. Cell service is good so you can figure out how to get back to Emeryville by bus, Lyft/Uber, Zipcar, train, etc., after you know where you tucker out.