Good embedded database solution (like SQLite) for .Net

The only other option I have any experience with is Microsoft SQL Server Compact if you don't want to install anything on the user side. SQL Server Express works as well if you did want to install something. It really all has to do with what features you want to have in your embedded database.

The one advantage of SQL Compact is that when its on a local drive i.e. not on a network drive it natively supports multiple connections. If you want it to write to a database on a network drive though you'll have problems with it. From your brief description it sounds like SQL Compact is what you want. If you have more specific requirements the answer might be different.

You can also check Firebird who has good dotnet driver

The embedded version is an amazing variation of the server. It is a fully featured Firebird server packed in just a few files.

dotnet driver here

From your requirements I would definitely recommend sticking with SQLite. We use it extensively and have found it to be a huge advantage over other options. Single DLL, integrates really really well with .NET, and is very fast.