Investigate the sounds that her Mom is making.

You put your ear up to the door.

She's moaning.
You can hear the subtle sound of...she's fingering herself.

You peer through the crack and the MILF is laid back first on the bed.
Her legs are spread and she's fingering herself.

As you go to leave, she starts talking dirty...

"Oh yeah- fuck my Daughter and then come fuck me!
Yeah, you're a dirty boy!"

Oh my.

"Stick it in me. So big. So thick.
Hitting me deep."

She sounds hot.
Classic MILF.

"Fuck me. Nice and hard. Do it!"

You get a look inside again and she's in doggy position.
She's finger fucking herself hard.

"Fuck me harder than you did my Daughter. I like it rough!"

She's nearly at orgasm.

It feels like the right time to enter.
If all goes well, you'll make another entry.