Can I send photo from my iPad to android mobile device?

Yes, use Dropbox.

You can email it or use an online storage solution such as google drive.

I meant by Imessage. She never chacks email or Dropbox.

If the iPad is connected to an SMS capable iPhone and you use continuity - you can send a text - NOT iMessage - iMessage can only be sent between  devices

Use Continuity to connect your iPhone, iPad, iPod touch, and Mac - Apple Support