Big headache - tenant won't move after lease expired

[Clara Tang]

She told us she would not renew the lease in Jun as she bought a house and would close in July.  However, on July 30th, she said her closing date was postponed to Aug 9th and she wanted to stay until Aug 10th.

We found our new tenant in July and signed a lease with them starting Aug 1st.   But they were flexible with the move-in date so we renewed the lease to a later date, which is not so bad as we plan to install new floorings before they move in.

Now the old tenant is not cooperating -

1. she does not answer our phone

2. we sent her the addendum with the original rent proportioned by date but put on a late fee $500 per day after Aug 10 (to motivate her to move!).  She changed it to $50 without telling us, signed and sent it back (we have not signed it) so basically, I think, a, she knows there is a possibility that she won't be able to close on Aug 9th and she plans to stay! b, has she conducted a contract fraud?

3. the addendum said $532 be paid on Aug 1st.  she paid $500 on Aug 2nd.

4. her mom (not on the lease) keeps sending us long texts, saying she is working on our property, fixing up, and charging us $25 per hour.   Saying we had not maintained the property.   And she threatens to report us for mold and fire hazards.

Fact: we fixed things she reported and for the past four years, she was a pretty ok tenant.  She was a PhD student now post Doc. and a single mom, that's why we had tried to be accommodating.  The mold she was talking about was a roof leakage 3 years ago, which we hired a company to fix it.  We sprayed the anti-mold thing to the ceiling.  They only told us three days ago there were dark marks.  and also in 2019, she reported dishwasher leakage, which we replaced with a new one.  She told us there was water damage to the floor but it looked ok until three days ago they removed the floor and sent us a picture it was black.  The fire hazard was ridiculous as we replaced the fire detectors 2 years ago, but she said they were yellow and old.

We are in VA. What shall we do now?