Is shagun doing all this to get ashok or raman?

Kyuki ab toh raman bhi rich hai...hot hai...

Aur ashok is anyways her 2nd option

She doesnt mind any of them

In my opinion, the idea of causing a rift between Raman and Ishita wasn't even in the plan for her before. I think initially she was just protecting Adi because she loves her son. Heck even Ashok doesn't know that Adi is the one who did the accident, he thinks its Shagun too. And then once Raman found the car and she again confessed to her being the one who caused the accident (to save Adi initially again), that's when she realized it could be used and was in a way driving a wedge between the two. That's why she made the picnic plan (spontaneously) to deepen the divide and show Ishita that Shagun still matters in Raman's life. And once the plan started to divide the IshRa, she probably noticed Ashok's reaction and thus got the idea of getting him to propose to her. Thus killing two birds with one stone.

Shagun does not really come across as a meticulous planner to me. She's very impulsive and goes with the flow usually and makes up plans on the spot. That's why she always ends up being embarrassed or having her plans flop, because they aren't fully thought through. Whereas Raman is the exact opposite in that he thinks a lot more carefully and plans ahead, which is why his plans tend to be successful (although if this entire track turns out to be some sort of master plan of his I will be annoyed).