Hi!madhura.jois,
Welcome To HealthcareMagic forum,
Pimples  are multi factorial, with reasons ranging from wrong selection  of creams and soaps to internal 
hormonal disturbances(esp in females).She  should avoid all oily stuff on her  face right from oily soaps to moisturizing creams. 
If your daughter has any  problem in her periods or her 
acne  aggravates 2 days prior to her periods ,then you should get a hormonal profile done with a 
ultrasound of lower abdomen. If some  thing comes positive then she needs a hormonal treatment along with a anti acne treatment This would mean that her acne is because of her raised hormones. If not then you have two options –either oral retinoids(for sever acne) or 
oral antibiotics depending upon the severity. They need to be taken for long .Also use a good anti acne soap daily. Its mandatory to use anti acne creams like 
nadifloxacin or 
clindamycin  cream.Oral Retinoid is a wonder drug for acne but before taking one should discuss all the precautions and side effects of it.(esp in females). All these require a medical prescription and you should show to a 
dermatologist   for this.Drink plenty of water and take a god 7 hr sleep in night .Never squeeze your pimples or else they would leave marks.
Acne is 100% curable if you take a good line of treatment.
Regards,
Dr.Chawda