Backdated H1B approval for amendment - Enter US ? Port of entry?

Need an urgent help based on your experience with regards to backdated approval , am on H1b ( no 140) , I’ve received an approval dated 11/30 form an amendment for change in client and location , need your advice

Company : ABC , Client XYZ

Filed an amendment in March 2019 , got an rfe which was responded in September 2019 , case approved on 11/26 , my employer received an approval notice till 11/30

My earlier petition was for same employer ABC but different client AAA which had a approval date of 04/30/2020 with I94 dated of 05/30/2020

In the above case what are my options

  1. Should I leave the country or stay back since my i94 for previous petition is valid till 05/2020?
  2. My employer will initiate an extension process with client XYZ tomorrow which would probably take 10-15 days max for lca + petitions filing , in this case can I be in the state for these 15 days ?
  3. My family is on vacation and their return date is 20 December, can they come back with existing stamping approval valid till 04/2020 spouse applied for H1b fy2020 ,received a RFE which was responded on 11/24, if I file for my extension now should I be filing her extension based on my petition

If the amendment start date is now, the previous approval may not be relevant as you applied for amendment and it is approved. If there is a question at Port of entry on where you work, they cannot say you still work at old company as that is not valid as client changed.
I would suggest you talk to your attorney and make a decision as he knows your case the best.