There have been two version of DB2 Express-C 9.5, versions 9.5.0 and 9.5.2. The current release of 9.5 is 9.5.4a. You can see which APARs got fixed in 9.5.3, and 9.5.4, and 9.5.4a at the fixpack download site. The same APARs generally apply to all editions.
The only version of DB2 Express-C available for download right now is 9.7.0. It has most (or maybe all) the fixes that are contained in 9.5.3 (but not 9.5.4 fixes). But there may be some new bugs included as a result of the new 9.7 features.