Thanks. She married in March and her husband is also Thai. They have bought a house and land already.

I don't know about the "Miss" part but apparently the law changed last week and women who marry are no longer required to take their husband's name. see below, it's from these boards.

http://www.thailandguidebook.com/cgi-bin....0;t=137

Changing name when marrying
 

I have a Thai friend living in Thailand. She recently married but did not adopt her husbands family name. She kept her own family name and is still officially called "Miss".

Can anyone tell me if this is common practice in Thailand?
Thank you.

Is her husband farang? Did they register the marriage legally with the Thai government? If he is farang and they did not register the marriage, it is probably so she can still buy land and a house. Otherwise, I have no idea why she wouldn't change her name to that of her husband.