Thank you for your query.
What mile stones she attained till now?
What is the extent of the delay in mile stones?
And she needs evaluation by a developmental pediatrician
to look for the causes, extent, and the domains of developmental delay so that early intervention measures can be advised to help the child.
You can give vitamin D sachets in prescribed dosage weekly once for 5 weeks for vitamin D deficiency after consulting your regular Pediatrician.
Hope I have answered your query.