When my mom passed a 4 months back, Abby her cat would call and call all night walking from room to room looking for my mom. We had to pack and move my mom's things pretty fast as her landlord wanted the space (the day after her death in matter of fact) so she didn't even have the comfort of a familiar home. She went to live with my sister and they kept finding Abby asleep in the bathroom on the mat. It was the only thing not packed and out that was washed in the same soap my mom used.
Try giving her something with a familiar comforting scent, cats are highly scent related animals. It may help bring comfort as she adjusts.
You may also want to try Feliway, it may help calm her.
Other people may have other ideas.