We use the adverb eventually to mean 'in the end', especially when something has involved a long time, or a lot of effort or problems: I looked everywhere for my keys, and eventually found them inside one of my shoes!

Which type of adverb is eventually?

In the end.

Is eventually a sentence adverb?

Eventually is defined as at an undetermined time in the future. An example of eventually is the adverb phrase "eventually have children," which means that at some point they'd like to have children. Finally; ultimately; in the end.