Like Jo said, there aren't really any "make nanny smarter" mods. I went through my mod list and found a couple you might find useful:
From Simlogical:
http://www.simlogical.com/sl/Sims2P...2_Childcare.htm
Crib Fix (prevents musical cribs)
Crib Get Out (lets toddlers get out of the crib themselves without screaming like a vocalist in a death metal band for five hours)
From Simbology:
http://www.simbology.com/smf/index.php?topic=10.0
No Smart Milk Drag (sims will make smart milk and drop it on the floor; the bottles can then be stored in the baby's inventory and pulled out when needed)
No Baby/Toddler Swarming (fixes autonomy so everyone in the house isn't queuing to play peek-a-boo until the poor thing hits motive failure)
Toddler Potty Fixes (toddlers can use the potty even if it is dirty)