This is a bit less quick and easy than David said, I think.
Law 13A said:
When the director determines that one or more hands of the board contained an incorrect number of cards (but see Law 14) and a player with an incorrect hand has made a call, then when the director deems that the deal can be corrected and played, the deal may be so played with no change of call. At the end of play the director may award an adjusted score.
So it seems this law does not apply, if the
♥7 was in dummy's hand when he took it out of the board. If that is the case, we need to find out how that card got into the defender's hand or his quitted tricks. Law 7B3 says
Law 7B3 said:
During play each player retains possession of his own cards, not permitting them to be mixed with those of any other player. No player shall touch any cards other than his own (but declarer may play dummys cards in accordance with Law 45) during or after play except by permission of the director.
The pertinent sentence is the second one - there is no suggestion in the first sentence that dummy should be penalized for allowing his card to be "stolen".

Assuming the TD determines that the defender violated this law, a PP is warranted except for very inexperienced players or in some special circumstance - the only example I can think of offhand seems pretty far-fetched, but the TD may, on investigation, find something pertinent.
Now we have a defective trick (Law 67). There are two problems here: the defender who has 3 cards left did not play a card
from her hand to the trick which contains the
♥7. So per 67B1
Law 67B1 said:
When the offender has failed to play a card to the defective trick, the director shall require him forthwith to expose a card face-up in front of him and then place it appropriately among his played cards (this card does not affect ownership of the trick); if
{a} the offender has a card of the suit led to the defective trick, he must choose such a card to place among his played cards. He is deemed to have revoked on the defective trick and is subject to the loss of one trick transferred in accordance with Law 64A2.
{b} the offender has no card of the suit led to the defective trick, he chooses any card to place among his played cards. He is deemed to have revoked on the defective trick and is subject to the loss of one trick transferred in accordance with Law 64A2.
So the defender places an appropriate card into that quitted trick (from the three remaining in her hand), and she is deemed to have revoked. More on that in a moment.
The
♥7 is put back in dummy, where it belongs. Law 67B2 applies to this card:
Law 67B2 said:
{a} When the offender has played more than one card to the defective trick, the director inspects the played cards and requires the offender to restore to his hand all extra cards*, leaving among the played cards the one faced in playing to the defective trick (if the director is unable to determine which card was faced, the offender leaves the highest ranking of the cards that he could legally have played to the trick). ownership of the defective trick does not change.
{b} A restored card is deemed to have belonged continuously to the offenders hand, and a failure to have played it to an earlier trick may constitute a revoke.
(The footnote deals with defender's exposed cards, so is irrelevant here). There is no penalty to the declaring side.
Law 64A2, referenced by Law 67B1, simple says that
Quote
and the trick on which the revoke occurred was not won by the offending player* then, if the offending side won that or any subsequent trick, after play ends one trick is transferred to the non-offending side.
Presumably the offending defender did not win the "revoke" trick, so this just says it's a one trick penalty. Even if the defense did win it, 67B1 still says it's a one trick penalty.
If, in fact, the
♥7 was in the defender's hand when she took it out of the board, then Law 13A applies, but I do not see how the irregularity could have affected the play, so I would not adjust under this law. I might award a PP to whoever at the previous table messed up. Law 7B2 may have been violated
Law 7B2 said:
Each player counts his cards face down to be sure he has exactly 13. After that, and before making a call, he must inspect the faces of his cards.
There is no suggestion that failure to arrive at the correct count be penalized, so no penalties here.
So, in summary, no score adjustment, table result plus a one trick penalty to the defenders, possible PP to the defenders, possible PP to one or both contestants who last played the board. Score it as 4
♠ making 5.