Pa CS 6105, Enumerated Offenses, lists the laws, that if convicted, prevent you from owning firearms. DUI is not one of those offenses. Being on probation will have stipulations, one of which is usually not being able to possess weapons while on probation. You can still legally own them, just can’t possess them while on probation.
If she is a first time offender, without prior criminal convictions, she should be eligible for the ARD ( accelerated rehabilitative disposition) program, which would allow her to have the offense expunged upon completion of the program.
Once again, I highly doubt she is in jail, solely on a DUI charge.