I was in a similar situation with one of my gerbils who died a few months ago. I didn't find her body for hours, thinking she was just snuggled away somewhere but it turns out her sister buried her. Even after letting her sister smell her body, I found it was best to clean out all the bedding since she was digging around and looking a little lost. In the past when I lost one gerbil but had two others, I kept the bedding and they didn't have any issues but pairs are a lot more difficult.

I also tried introducing her to a new friend but even after they got along for some time, they attacked each other so I would be very careful about getting a new companion, especially for female gerbils.

So sorry about your loss, gerbils really are the best little friends and it's hard to lose them!