Wild ending
 

A has ball on own 35 yardline 4th and 10 with 10 sec to go in the game. Behind 23-22.
A10 runs to B's 10 yardline where he is about to be tackled and throws an illegal forward pass complete to A88 in endzone for TD.
The clock has ran out 00.00.
Give me options and Rule Ref.

What the answer on the NFHS FB group wasn't good enough? :D

Illegal Forward Pass is described in NFHS 7-5-2-a-e. In the penalty summary of Rule 7, the penalty for an Illegal Forward Pass includes BOTH a 5 yard penalty from the spot of the pass and the loss of the right to repeat the down.

B's options would include refusing the penalty and accepting the result of the play, TD for A or accepting the penalty, negating the TD and the loss of the right to repeat the down, with the clock having expired would end the game.

This issue got addressed several years ago.

Before this loophole was closed a few years ago, would there have not likely been a penalty for ineligible receiver downfield?

Those restrictions only apply to a legal forward pass.

Who would have been ineligible?

My thinking was that if the ball carrier has run 25 yards before throwing a pass, than every offensive lineman is more than likely run blocking well downfield. But, I see though from Welpe that this rule wouldn't apply since it only applies to legal forward passes.

Think about what the purpose of the eligible receiver rule is......

I'm going to switch this up.

same situation, but the game is tied. A10 throws an illegal forward pass on the last play of the game and it is intercepted with the intercepting player going down in bounds on the play after the clock hit 0:00.

My understanding is the in this situation, time has still expired since either option for B would result in the time expiring. We move on to OT or have a tie game. .

Sounds correct.