Possible mantidfly larvae

One of my coworkers had a garden spider (I believe an Argiope aurantia) outside for a number of months. She produced several egg sacs and then passed. We waited months for the egg sacs to hatch, but they never did.

It may be a bit odd, but we collected one of the egg sacs in a jar, and kept it as a keepsake of the spider.

Several months after that, these small things emerged from the egg sacs. I think they may be a type of parasitic larvae that was feeding on the spiderlings. My guess was they were a type of mantidfly larvae, but was interested if someone had a more accurate ID. Thanks.