Use an android phone as a monitor screen with AV-in wire?
Use easy cap ... 
easy cap is generally used for fpv in multirotors which has also the same purpose as yours. It takes an av input and decodes it to give an output in the phone.
Check here..
http://www.amazon.com/EZ-Cap-EzCAP168-Capture-Software/dp/B008I679QG/ref=sr_1_1?ie=UTF8&amp;qid=1464120381&amp;sr=8-1&amp;keywords=easy+cap