Check each out such as listed by http://blog.capterra.com/free-event-management-software/ then if it falls short the fact some are open source means you can add the missing feature and improve the app.
However I am running into folk that don't understand opensource. That is, they found it upsetting that one of the ideas of opensource is that we can add missing features. A few get upset and flame over that.
If you don't code, you can feedback to the authors and ask for a new feature.
I am looking for an opensource/free event form software similar to Google Forms for corporate events, but it needs to be able to save user data and auto populate the fields if they come back to enter information for another event. I have been unable to find anything like this are would really appreciate any input.