Strong lay down?

[KCFire105]

Ring game, $200 buy-in $2-$5 blinds.
Hero 7-7 MP limps in.
Button ?-? limps in
Villan ?-? BB checks.

FLOP- 7-9-Q

Villan in BB comes in for $30.
Hero makes it $70 to go.
Button calls $70.
Villan calls the $40 raise.

Turn- 7-9-Q 8

BB Villan checks.
Hero bets $80.
Button calls $80.
BB Villan calls $80.

River comes. 7-9-Q 8 9

Immediately BB Villan goes all in for $270.
I (hero) have $180 left with one potential caller behind me.
After much deliberation, I conclude I have the worst boat (an under full) and lay down because the only hand I beat is a straight (many more boats beat me, and made it since with the betting).

Button lays down.

With no callers Big blind Villan shows 10-J for the straight.

How many callers in 2+2 land in my position with the underfull?

Strong Laydown or not?