The landline contract can be cancelled with a 3 months notice period beginning the earliest by the day of your move but not earlier than by the day you notice Vodafone about your move. Also note that you will need to provide proof, e.g. a copy of your deregistration notice (from the townhall).
This information should be sent in German language to Vodafone - I cannot give you the correct address as this depends on what kind of landline contract you have and where you live (which federal state).
So you will have to pay for at least 3 more months beginning by the day you move out of Germany (or your notice is received by Vodafone if this is after moving out of Germany).
The mobile contract anyhow cannot be cancelled prematurely as you are able to use the contract abroad as contractually agreed upon. You can only cancel it at the regular end of the term (initially 24 months), whereas your cancellation request has been received by Vodafone at least 3 months (the notice period) before the end of the term.
