Re-entry of visitor visa holders

[karthik81]

My parents are holding multiple entry B1/B2 visa. They were in USA from Jan'16 to Apr'16 after then gone back to Canada staying there from Apr'16 to present (6 months). I am planning to get them back in the USA by end of this month. Will there be any questions asked about not returning back to home country, during there port of entry? denied entry to the USA or cancellation of there US visa? please advice.

[jnk]

Yes. Most likely immigration officer at the port of entry will raise that question. May not cancel the visa but can give verbal notice or deny entry.