Home budget app is good, something I have been about to do also when I have time. Make it easy to use, have enough features, some charts or other data visualizing and perhaps store the information securely online so it isn't device dependent.

But keep in mind that home budget apps are very common and to get visibility to your application will be hard because there is lots of competition.

PS. Don't make it look like the one you posted as that looks like it's at least 5 years old. Try to make your application look appealing and modern.