Check the contract. Some vendors require a meal, others do not (and in that case you can either offer some food or not, but it would be considerate to ask them if they'd like you to arrange for food for them).
If they're working, then if they get a meal or some appetizers it won't be at a table with guests. The hall probably has a side room where vendors can store their stuff and eat. It's not like she'll be sitting at a table with Aunt Bertha and chatting.
If your reception is at a hall or is being professionally catered, then talk to the staff about how they handle vendor meals. In most cases it's either free or cheap (not the cost of the guests' plates, anyway) to feed them through the caterer. Sometimes you can have different food for them, in which case you can have pizza or sandwiches delivered if you wish.
At my wedding I asked all the vendors if they needed a meal. I had a DJ who said no thanks, and two photographers - the second photog/assistant left before dinner so she didn't need any food. The main photographer said he would make himself a plate of hors d'oeuvres at cocktail hour, and he also had some dessert and coffee near the end of the night ... so he ate, yes, but he didn't want a formal plated dinner like the guests got.