My condolences for your loss.

Your sister could make an appointment with the Genius Bar at any Apple
store. The only issues with Apple stores are the crowds and the technicians
can only offer Apple based solutions, even if there are cheaper non-Apple
solutions available. I use the following one:
Biltmore Fashion Park
2502 East Camelback Road, Phoenix, AZ 85016
Phone: (602) 606-1470
Hours:
Monday 10:00 am – 9:00 pm
Tuesday 10:00 am – 9:00 pm
Wednesday 10:00 am – 9:00 pm
Thursday 10:00 am – 9:00 pm
Friday 10:00 am – 9:00 pm
Saturday 10:00 am – 9:00 pm
Sunday 11:00 am – 6:00 pm
Transit: Camelback Rd & 24th St

There may be one closer to the person who needs help.

The other Mac alternative I use is MacMedia, Inc. The folks in the
Scottsdale store are very knowledgeable and helpful. I tend to use them
more often because I hate the crowds at the Apple Store...;) They are also
not forced to recommend Apple only solutions - they offer Apple and
no-Apple solutions (including lots of open source solutions!) and you can
pick the price/alternatives you want.

6928 East Fifth Avenue.
Suite 1
Scottsdale, AZ 85251
480 964-6352
Store Hours
Mon-Fri 9am-6pm
Saturday 10am-4pm
Sunday Closed [Peoria Open]

15525 N 83rd Ave.
Suite 108
Peoria, AZ 85382
623 850-8000
Store Hours
Mon-Thu 10am-7pm
Fri-Sat 10am-8pm
Sunday 12pm-6pm

Given your sister's situation (and perhaps a copy of the death certificate)
I would hope neither store would charge anything for helping her.

Good luck!

Mark