See a qualified CPA to prepare your taxes. Since your wife passed you probably have a few other things to deal with. If you were married at any point during the year you may file married/jointly.
This is not legal advice nor intended to create an attorney-client relationship. The information provided here is informational in nature only. This attorney may not be licensed in the jurisdiction which you have a question about so the answer could be only general in nature.
Yes you can file married filing jointly 9or married filing separately and claim her as a dependent) and include the out of pocket medical expenses on Schedule A (Itemized Deductions) (The medical expenses will only reduce the tax if the total medical expenses exceed 7.5 percent of your adjusted gross income and the total itemized deductions exceed the standard deduction.