My landlord lost the property, The bank voided my lease and put me on month to month. I will not show the property to potential buyers. My Doctor has sent the property management company and freddie mac and Doctor statement that My family and I are under Doctors care until further notice, how long will this last

About the time it takes them to file the doctors note away.
They don't care you are under doctors care, they want to sell their property, next they don't have to have your permission to show the property, they should have a key to the home and have a lock box on it, to show it when you are not there.
If not, they could merely change the locks ( giving you a key) and do this.

If you are stopping the sell of the home, they may even sue you for possible losses, and for sure evict you. And if you are not working with the lender, don't expect the housing court to have any nice feelings.

Next at best a "doctors" issue may get you a extra 30 days in an eviction, that is about it.

Why are you not cooperating with the owner of the home to show it? Are you afraid someone is going to take your belongings? Your doctor's note is meaningless in regards to not showing the property. The owner of the home may decide to just terminate your month to month lease in order to be able to show the property.

When did this foreclosure take place? In May 2009, a law was signed into effect that required an existing lease be honored. So the bank may not have legally been able to void the lease.

In addition, they must allow you 90 days notice of termination of your tenancy (see here: https://www.askmehelpdesk.com/real-estate-law/paying-rent-when-property-foreclosure-316199-2.html)

However, you cannot refuse to show the house at reasonable time and notice.

When did this foreclosure take place? In May 2009, a law was signed into effect that required an existing lease be honored. So the bank may not have legally been able to void the lease.

In addition, they must allow you 90 days notice of termination of your tenancy (see here: https://www.askmehelpdesk.com/real-estate-law/paying-rent-when-property-foreclosure-316199-2.html)

However, you cannot refuse to show the house at reasonable time and notice.

Yes. So although you may be on a month-to-month, they need to give you a 3-month (+) notice to evict you.