She has been in the hospital with covid 19 since dec 30 and now just tested negative today how long should i wait to see her?

Ask if it was PCR or rapid as the PCR is a more durable response and reflects elimination better. Some may be rapid negative but still PCR positive -though it is assumed they are no longer infectious at that stage but in this era would be cautious and ask for PCR. .

If the infection started Dec 30 or before and she tested negative & has been absolutely without any symptoms for 3 days she should no longer be infectious but she and you could mask and socially distance for a few more days to be sure.