Stephen Archer and a penalty try in the second half demonstrated the Irish side's continued intensity with Stander getting his second in the 78th minute.
Munster are two points behind Ulster in the league standings following the five-point victory having won four of their opening five games.
And O'Mahony, who was making his long-awaited return from injury, was impressed with the energy and intensity the Munster replacements brought to the game in the second half.
"To be fair the lads had the bonus point by half-time but the subs had a chat and we had to make an impact when we came on," he said.
"Not just for selection but we've had teams under pressure and not finished them.
"Credit to the bench who came on, we kept the pressure on and our foot on the pedal and we ended up nearly on 50, we are happy about but there's stuff to work on obviously."
O'Mahony damaged his cruciate ligaments at the Rugby World Cup last October, but was delighted to finally make his Guinness PRO12 return.
"It's great to be back, it's taken a long time probably about 12 months since I played rugby and probably about 18 since I played for Munster," he added.
"It's a great feeling coming back and playing at Thomond Park is always special.
"I was blowing hard there for the last few minutes but that's a great feeling. It's a great feeling to have when you haven't had it for so long and it's one you probably take it for granted."
Guinness PRO12 Final 2017 Ticket Information: Fans can save up to 20% on selected tickets, and prices start at just €30 adults and €5 child, and be booked via www.ticketmaster.ie. For further information visit http://www.pro12rugby.com/final
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