Halloween is a traditional festival in the West. On that night, children will wear costumes and masks and go door to door to collect candies. Since she is your bestie, you should know her preferences very well! Here are some suggestions, I hope they can help you:
Many people will choose to give some chocolates and candies. If you want to have fun, you can DIY a handmade chocolate and write some funny words on the chocolate. Of course, you can also consider making the chocolate into a pumpkin lantern;
Customize a sunshine jar for her online and draw some memories of the two of you on the jar.