She has sincerely apologised. I for one accept that her apology was genuine and sincere.
Was it really genuine and sincere though? Because initially she said she was ‘checking’ the property, which gave the impression it was some kind of necessary purpose to do with securing the house or similar, but it now seems that the whole family actually went two weekends in a row, so it was clearly actually for fun / leisure.
What that shows is that she clearly doesn’t think she needs to follow the guidelines (probably because she thinks she can rely on her own judgment, which might be true for her but would be very problematic if everyone took the same approach). It wasn’t a mistake, it was a conscious decision not to follow the rules she is telling everyone else to abide by, twice.
I don’t see how she can continue to tell everyone what to do when her behaviour has given everyone the impression that it’s actually ok to not follow the rules now and then when it suits you?