Person 'X' and person 'Y' live together.
You bump into the person 'X' on street and what to ask the 'X' about the person 'Y'.
How would you ask informally how a person "Y's" life is going during your greeting?
I can think of four sentences, but I have no idea whether they all naturally and idiomatically work in this sense:
a. How's everything with 'Y'?
b. What's up with 'Y'?
c. How's it going with 'Y'?
d. How's 'Y' doing?
If no, then please let me know how they do not work and what is the best way to ask about such that thing?