my baby became too clingy all of a sudden and cries out loud whenever my wife puts her on mat. Why is that?

This depends a bit on how old you're child is, but you're little one is probably going through a new development stage. She either learns that she isn't a part of the mother anymore and feels separation anxiety. Or kids tend to get clingy when they learn a lot of new things in a development stage. Check out Wonder Weeks on these phases.