Fix hacked wordpress website (content injection)

Job ID: 31253282

Budget: $30 – $250 USD

My website seems to be hacked, since conteent is injected to our pages.
If i normal open the page it looks good, if i open as spider it has injected content. See: https://webcache.googleusercontent.com/search?q=cache:x6SrGeNz7VMJ:https://www.rlly.nl/autopuzzeltocht/+&cd=4&hl=nl&ct=clnk&gl=nl

I placed back a backup and updated everything but hack returns.
In your bid, pls describe if you have experience with this specific hack ans solving this.
Related categories: PHP Web Security WordPress HTML