Again as Debbie mentioned, you should also consider collecting a lease commission.
Most least options pay the listing and selling broker a commission once the option is executed. If you are looking for a commission at the signing of the lease you must put it in the agreement that you will be paid upon execution of the lease. It is possible to get perhaps 1/2 of the commission now and the balance at the purchase. Hope this helps
Wendy Patton, a Michigan Realtor and a proponent of lease-options, has developed a strategy whereby the agents can get some, much, or even all of their commissions up front. Here's a link to an article she wrote addressing the topic: http://www.wendypatton.com/articles/getting-realtors-begging
Basically, as much of the commission as possible is paid from the up-front option fee paid by the tenant-buyer.
Hope that helps.
If she is the listing agent and the seller decides to enter into a lease with an option to buy arrangement, rather than just outright sell the home, as the listing agent and a party to the transaction, any listing agent would expect to be paid the listing commission at the end of the period, if the option is exercised.
Any commission should be stipulated in the contract.
At the very least, a rental commission may also be due, as there is no assurance that the sale will take place at the end of the lease.
Read your listing agreement and the option contract. Chances are, if the option is exercised you will get paid the sale commission. If not, you may get to relist the home for sale. Hopefully you get a partial commission for the option.