If the deal looks like it will fall through, you can always lease-purchase the home to her. Give her a 1 year lease, and tell her in 10 months she needs to activate the purchase, find her own funding and close by the end of the lease. This way, she's making your payment, you get to move, and if she doesn't activate, you have 2 months to relist and sell. This option may not help you if your new purchase is contingent (sp.) on the other closing.
if it is just a 1 yr lease, both parties won't like the amount the home will be worth a year from now. If you were to do a lease option, I would set it up for at least 5 years, preferably 7 and tell her any equity from what you agree on today is split 50/50 when she excercises her option.
Just my opinion though.