I'm betting that if Yang is actually going after Raven like a bunch of people think, when she and Ruby reunite, Rubes will be very supportive of Yang's decision. Because it's something that she's wanted for YEARS, and honestly I think Ruby would feel a little guilty if Yang decided to go after her and not her mom. However it's also possible that she's going after Ruby now and Yang simply says Ruby is more important than her mom. Either way works for me.
Yep, Ruby would be totally supportive of Yang doing her own thing. She said as much in her letter - that she wanted Yang with her, but understood that Yang had to take care of herself.