There are a few reasons for a "false positive' result on the skin test:
---having received an immunization for TB, called "BCG" (this is not usually done is the U.S., but is done in other countries)
---currently has (or had in the past) a Mycobacterial infection, that is not actually TB
---had a previous infection with TB, but does not have a current active infection
---the skin test was improperly administered
There, of course, is the possibility that she has been exposed to TB. The facility most likely has procedures for following up by doing some more testing (usually an exam by a physician, and a chest xray or CT scan) to determine if she has been infected with TB. Until this is done, you will not really know.
The facility "community" is at high risk, otherwise they would not do testing so frequently. So, I would advise that a visit by her baby daughter be put on hold until your daughter knows what is going on.
If it turns out that she has a TB infection, there is treatment for it.