I finally found the track which is inspired by ada's theme in re2. It was brought back in re6 but it's missing in re2r. Thankfully re4r brought the track back. This is one of the best tracks in the series to me.
Here are the versions from re2 and re6 as comparison. For re6, it also comes back during the credits sequence of ada's campaign, it's very heartwarming to hear.