Tenant wants to break the lease due to medical issues.

[Elena Pech]

I sent a lease renewal letter (4 months before the start of the new lease with no rent increase). In a few days I got response from the tenant that she just discovered a serious medical issue, is on the way to the airport to start treatment in her native country, will be back in about 6 weeks to pack and move out. She wants to move out about 2 months before the end of her lease and she wants her last month and security deposit back.  If this is a real emergency situation I can allow it and start looking for a new tenant, but is it appropriate to ask for any medical papers? What is a right approach? What's the purpose to sign the lease if it can be broken just like that? What would you do?