Best starting lens set
If so, it's weather-proofed.
One concern will be water spray/rain on the front element. Nice for some shots — but not ALL.
If it's salt spray, she'll need a way of dealing with that.
Greg (Daddyo around here) is high on the 2x in-camera teleconverter feature, which doubles the reach of any lens you use. He says it's better than cropping later. If your sister only has the 12-50 and wants more range on some shots, she should keep that in mind. (And make sure to turn it off when not needed.)
I'm not talking about the 2x conversion-to-35mm-speak factor of any Olympus lens. That the 12-50 lens is 'equivalent' to a 24-100 lens is a given. This digital teleconverter turns it into a 48-200.