Hi S.,
I as an In-Home child care provder myself, and a mother I can understand. All of my daycare kids go down for nap at the sametime.
My 2 kids that are at home are 20 months and 4 yrs. The other kids I watch are 21 months, 18 months, 4 months and 3 yrs. Even the 4 month old goes down with the older ones at afternoon nap.
I have a couple of suggestions
If she sleeps with something specific at nap, send that or the same with her.
Also make sure your provider is leaving her in there to nap for a reasonable amount of time. All of my daycare kids and my kids will nap for 3 hours or so. But if someone wakes up before that time like 30 minutes to an hour I go in and lay them back down. An hour is reasonable but mpt 30 minutes. Also it could be she is over tired and she feels she misses out on a lot taking a morning nap and she will miss out on taking an afternoon nap.
We did away with 2 naps a day about this age here because of this reason.
And the other part is her schedule and routine may be a little off from what yours is at home.
Anyway, whatever works just communicate with your provider on what the next step should be.