Gastric adenocarcinoma w/ lymph node involvement---- 9 out of 26 tested positive. Are there options after the gastrectomy for 87yr old or too risky?

Possibly. Options for postoperative treatment generally include chemotherapy and/or radiotherapy. While many 87 year-olds will have difficulty tolerating these treatments, everyone is different. Some elderly patients who have a good performance status and few comorbidities can tolerate aggressive treatments.
Yes. If an 87 year old tolerated the surgery, then i would consider the chemo. Overall, the prognosis is poor with the staging you are describing for gastric cancer, but if you did the surgery, which is a big deal, why stop there?