I don't think Anne is afraid of meeting the Crofts as such; she just doesn't want to meet them for the first time in her old home. She avoids visiting them at Kellynch Hall the first 2 times, but the third time, when they come to Uppercross, she is quite happy to meet them.

Anne had very sincerely rejoiced in there being no means of her going [to Kellynch Hall]. She wished, however, to see the Crofts, and was glad to be within when the visit was returned.

As for her insisting on staying with her nephew, I think that by the standards of the time, JA expected her readers to honour, not criticize, Anne for it (even if it was also a great excuse to avoid meeting CW!). As I mentioned in another post, in JA's other novels it's obvious that it was considered wrong to leave a sick family member alone with just the servants, and in this case Anne is taking the place of Mary, who is clearly failing in her duty towards her son.