Ave Maria is most holy prayer of Roman catholic christians which is sung mostly. Other christians also like it. If there is national anthem of catholics/Vatican it will be this.
I don't see any relevence or connection to eid or to president(of pakistan) or zardari.
I think this episode comes under blasphamy law.
If you use copyright recorded material without permission it will be under copyright law of pakistan and other countries, in this case singer's voice.