Acquired Company with SIMPLE IRA

I realize this topic was discussed in the past,  but want to see if anything has changed.

Company A has a SIMPLE IRA
Company B has a 401(K)

May 1, 2018 Company B purchases (stock purchase) Company A.  Company B wants the employees of Company A to participant in the 401(k) Plan. The SIMPLE will remain in place ( "frozen") until it can be terminated.

My initial thought was Company A employees cannot defer into the 401(k) Plan until 1/1/2019.  Their contributions would continue to be made to the SIMPLE Plan for 2018.  Company B would make the employer contribution.

1. Does Company B have to continue the SIMPLE Plan - could they leave the plan alone ( no contributions) until it can be terminated?

2. Is there any way the employees of company A can defer into the 401k plan for 2018? Or are they out of luck?

thanks