"What "share" and how does that apply?"

The Traditional IRA  (Acct #1) the $8,000 was distributed from is in her name and grandmother's name + (Decd). There were no contributions to this account. Basis is $50,104

Correct. Secure Act applies. The $8,000 is an RMD.

"Withheld for Fed & State Line 7 = 4"

Line 7 = 4 = Death

The 2021 $6,000 contribution made on behalf of the taxpayer was a different account - a Roth IRA (Acct#2) only in the taxpayer's name.

"Do you know how long the deceased's IRA account existed? If that is/was also Roth, this matters."

This was a traditional IRA. Do not know how long account existed.

"Roth Account Value as of 12/31/21 - $5,978.92."

This relates to Roth - Acct #2

Thank you!