What do you think will make a bigger impact on consumers - 1. a celebrity endorsing the product or 2. the brand supporting an important social cause which will help the society. Kindly share your views?

It depends on the consumers' preferences - you can make small survey to check it as each country is different. From my experience in FMCG - I would say celebrity.

it depends on your customers, you should study your consumers preferences first.but from my experiences celebrity endorsements have been more successful in many cases.