S.C.
I wouldn't have her call right before bed. I would have her call after dinner. You don't want her sad before bed and maybe if she talks to them earlier in the day she won't miss them as much when it's time to settle down for sleep.
Just a thought but does she do this at bedtime to stall? I'm not saying she doesn't miss them, but why does she only really get upset at bedtime? My daughter did this for a few days. I let her call her dad one night. Next night it was grandma. Next night it was dad again. Next night I told her she can call anybody in the family she wants, but no more at bedtime. She needs to call before bedtime. She hasn't asked again.