While the RN-BSN will undoubtedly cost more in the long run as opposed to going straight to a RN-MSN program, there are benefits to doing a RN-BSN first. If you live in an area where BSN's tend to be necessary to get hiredin your daughter may have a hard time getting a job with her diploma. Also, if your daughter isn't sure what sort of NP she wants to be, then working as an RN while doing an RN-BSN program will give her time to get experience while she narrows down her field.
Also, there is no point in doing an RN-MSN program and then later NP school. It would make more sense to do an RN-MSN, with the MSN in an NP specialty, this way your daughter does not pay for two master's degrees.
Bottom line there is no right answer for everyone. It is ultimately your daughter's decision to make.