Does someone who has hidronephrosis can take pills to prevent pregnancy?

See below. Hydronephrosis may have left you with a reduced kidney function, which may affect your pregnancy. The doctor can help you understand the risks of taking contraceptive pills vs the hazards if any of a pregnancy with reduced kidney function. It all depends on the extent of loss of kidney function.
Yes. Yes but if you have reduced kidney function it is important to let your pcp or gynecologist know.
Yes. The hormones in the pill are metabolized in the liver so kidney issues are not a contraindication.