Ap for my parent

[jrvaidya]

Hi,i am us citizen and have applied for my parent's green card.their i 485 is pending,they had interview and officer told that they will receive an approval letter ,its been 4 weeks and nothing. they need to travel due to family emergency,i need advise for the following; 1 -they have overstayed more then 3 years ,is it ok to apply for i131
2--will they be able to come back to us ?
thank you in advance