Visitor Visa - B2

I had interview on 23rd of May, Islamabad US embassy. My profile 29 M, single, doing my family bussiness and my interveiw went this way.I reached embassy I was bit late, When I was in row for interview after fingerprints I saw 4 window that taking interview I can listen the interview of others.I was trying to skip from a lady who is rejecting applicants but unfortunately my number come at her window

VO: How are you
Me: I m good what about u.
 
VO:Passport plz
Me: Handed

VO: Why you want to go US?
Me: I want to see my grandmom living with my uncle.

VO: What your grandmom do?
Me: She doing nothing just stayed at home.

VO: Is your grandmom green card holder?
Me: Yes US permanent resident.

VO: How she get green card?
Me: Her son was US citizen by him.

VO: Have u traveled out of country?
Me: Yes

VO: When and Where
Me: Dubai twice in 2016 and 2017.

VO: What do u do for living?
Me: I m doing my family bussiness.

VO: What kind of business?
Me: told.

After that she turned to me and said sorry u dont have strong ties and dont give you visa this time. And handed me yellow paper with my passport

Through out the interview she was tying in system and look into computer.

I need sugestion what do for next when to apply again or need to make strong travel as mentioned on 214b yellow paper coz I m alread doing my business here. What strong ties required. Please members let me know.

Thank you