First class response!
Although I no longer do so (Covid, Old Age, and a more responsible Co-Host helped show me what I'd been doing for a few years) I used to provide a Welcome Pack that included more and more food and drink products as each year went past.
Even more, I always asked our Guests what they wanted by way of milk, butter, cheese, bacon, coffee, jam, chutney, marmalade, bread, ice-cream, yoghurt, plain or carbonated water, type of Ale, and many other items, so always had lots of happy Guests - many if whom used to take what they didn't use, home with them - for which I rejoiced!
Everything I provided was "free" to them, all were goods that were made in one part of the UK, and - at the time - not much of it was available elsewhere, BUT by their enjoying the items themselves, and taking back home with them other items, what this part of the UK made, usually ended up with either the Guests we'd had, wanting to return, or wanting to get some of the items sent to them, but also those who are or drank the gifts they received, often booked to stay with us.
Regrettably we no longer provide such a Welcome Pack, yet Guests' still love our place, and they still return, so obviously we're doing something right!
As to complimentary, I would prefer to use the similar sounding and written word, "complementary" and include the cost of the food/drink within your price, and ONLY provide to each guest the quantity that would mean they wouldn't abuse your kindliness.
Maybe you have local foods and/or drinks that could be left for your Guests, so that they too would like to have more in the future?
We are all on a journey in hospitality, so there isn't a right or a wrong way of doing anything, but maybe the person who took the lot really helped you more than you realise, for not only have many Hosts put their own spin on the topic, but I'm sure we've all learned something out of it!
Have a great future!