I think it will depend on the purpose for this cash giveaway. It could be an advertising expense if the purpose is to gather “likes” or contact info on social media from potential customers of the business. I have to assume your client is not just being charitable.
I am not sure if your question regarding the tax treatment pertains to the business giving the money, or the one receiving it. Assuming the former, I see no reason why it would not fully deductible as an advertising expense. The giving business would be receiving the goodwill of anyone reading the social media postings.
As for it being considered as a charitable donation, it wouldn’t qualify as the recipient is presumably not registered as a charity. A nice try, though, as the donation credit may well be worth more than a simple expense deduction.
If you’re referencing my comment about the client “just being charitable”, I meant that in the non-tax way. I wasn’t suggesting that anyone should be looking for a charitable donation receipt.