Visitors visa extension for parents

I applied for b2 visitors visa for my grad walk last year, they received only 1 year valid visitors visa, due to personal problems they did not come to us , in 2 months the visa is going to get expired not how can it be extended , is it a problem for them for not visiting usa even after getting visa , please help me , i want them to visit usa sometime next year.

It is no problem that they did not visit USA after getting visa.

Infact it strengthens their case. Technically parents are now eligible for Interview Waiver. But my feeling is they will be called for interview. However They have to submit the case as Drop Box case. If called for interview , let them explain the facts.

If yr documents are in order They should get the visa easily

thanks a lot for ur reply, what is the process now to extend the visa , what all the things i need to do

You have to start anew. Fill DS 160 form. Create profile , take Appointment after making payment etc.
While filling profile , system will ask you about previous visa ,whether issued after 2008, class of visa etc. Answer as per yr case . You will get drop box instructions. Follow them

profile , you mean while filling details in ds 160?

moreover my parents visa is getting expired on may 1st so when can i apply for extension , do i need to apply for extension before may or can i do it by the end of the year in nov or december also?

Profile means the steps that you have to take to appointment after filling DS 160.
They can apply anytime as per yr convenience.Evenif they apply in Nov or Dec it will still be drop box case