Sometimes, play dates don't always "have to" be planned and structured and organized. Kids this age are more self-directed.. .and they always find stuff to play or play with.
I have a lot of play-dates with my daughter's friends, sometimes I totally plan things out, and other times I don't...depending on my energy level, and how well I know the Mom. Either way, the kids always have fun. They ALWAYS find things to do and play with, whether or not I have things planned out. And, I just supervise them for safety or conflicts.
I also just make sure to have snacks and food for them.
I also make SURE I make a specific "time" for the play-date, and specifically say when it "ends" and when the Mom can pick up her kids....so you are not left to just entertain ALL afternoon or morning. I tell the Mom to be SURE to call me, if she is running late. Afterall, it's only common courtesy.
Or, if you are concerned about costs and your own family's food... just tell the Mom to bring her child's own lunch or snacks.
You can also tell the Mom to bring an extra pair of clothing for her child, in case they get dirty or wet.
Make sure the Mom also gives you her phone/cell number in case of anything....or if she is late in picking up the child.
Kids also like to cook...boys or girls. So we make cookies, or their "lunch" together. Cookie cutters are fun to cut out any kind of cookies, bread for sandwiches, bologna, or to mold rice with.
Or make pizza. Just buy ready made bread dough from the grocery store, (it's usually in the frozen or refrigerated section), buy cheeses, pre-made jarred spaghetti sauce, toppings etc. Then let them "help" and roll out the dough and make it into a circle. Then let them "help" you put on the toppings. Then put it onto a cookie sheet, and bake until done.
It's also fun to make soap. You just go to your craft store, and buy glycerin soap. Then break off chunks, put in a pyrex dish, and microwave for a FEW seconds at a time, like 5 seconds at a time, to melt it (you don't want it to bubble)... then, pour the melted soap into a "mold" (anything plastic like a small baby food container, oil the sides lightly so it can slip out later), and add food coloring, mix it lightly to combined the colors, then let it harden. Then, the child can take it home and use it. After the soap hardens in the "mold", just push it out, and voila! You have fun soap! The kids really love this when I do it.
Or, have a bug catching expedition in your yard. Give them glass jars with a top, poke holes in the top, they can decorate it, then go outside and catch bugs.
Or let them play in sprinklers in the yard.
Or, get fabric paint, some blank white t-shirts, and let them paint designs on it. You can get it all at your local craft store.
Or a game of kids charades. You can make it yourself on index cards. Then just have them act it out.
Or do crafts... paper plates can make anything. Or paint. Or paint rocks.
The game "Twister" is also fun for kids. My daughter and her friends really like it.
Or, get a fun video for them to watch, and make popcorn and fun snacks.
Good luck!
Susan