That is most definitely a very sad anubias. Not sure the specific species because of its condition.
The first thing I'd do is trim it way back. Any dead or dying leaves would be removed, even if it means that ALL the leaves are gone. The key is that the rhizome (the horizontal 'stem') needs to be a nice vibrant green color. If it is, it will grow back leaves. I'd also trim the 'roots' coming off the rhizome.
Ultimately, something is most definitely amiss with this plant. One thing to note about these plants... they are very slow growing plants under normal conditions. So, if they are kept in a brightly lit area (as this appears to be) it can lead to algae growth over the plant itself, leading to the leaves dying. So, any algae needs to be removed, the plant needs some light for about 6-10 hours a day, but not tons of light. There may be an imbalance in the nutrients, but generally speaking these plants are super easy and require nothing that the fish waste in the water wouldn't already be providing. Unless your water is extremely soft, I don't see the need to add any supplements for the sake of the plant. If, conversely, the tank is extremely lightly stocked and you have have soft water, then adding some ferts would give it a bit of a 'boost'.
You might also want to consider splitting the rhizome. It appears to have some 'branching' happening along the rhizome. But, I wouldn't split the rhizome until the plant starts putting out some fresh leaves and the leaves are a fairly nice size. Then, don't trim the rhizome to be a section any smaller than having at least 3 full sized leaves on it.