What alternatives are there for hip pinning surgery for my 100 yo grandmother?

Bedrest: In general, with hip fractures the choices are surgery with improved mobility or no surgery and bedrest. Surgery does increase the short term risk a little but patients tend to do better with having their hip fractures fixed than without. Prolonged bedrest leads to bedsores, pneumonia, and a high 6 month mortality rate. Talk with the orthopaedic surgeon about your grandmother's case.