I see no problem with it.
If she chooses to get it "implanted" in, than its the same way someone takes a tylenol pill to quickly heal a headache. The "natural" way is to just let your body be and eventually you will naturally overcome the headache.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=5274
I dont see anything in Sikhi which would tell us to run from medicine or new technology, specially if it includes to bring a new Khalsa into the world. She's not doing it for any of the evil reasons, she's not going to have this baby just try to take over the world, or create evil.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=5274
If she chooses to have a surrogate mother come in, than I see it just as an extreme form of a seva by the other person. To be 9months pregnant with someone elses baby is an extraordinary deed, and its just pure seva. Once again, its bringing a new Khalsa in the world.
She's waited 28 years, which is extremely long, I would tell her its ok, and dont see a reason why someone would say its wrong.