Studies show that advanced age is a predictor of poor function after hip fracture. Although it is entirely possible that your husband will regain independent mobility, only two per cent of the population aged 90 and older are able to return to their prefracture level of independence.
Many older adults end up using a walker but are able to gradually progress in their rehab program to use two canes. Eventually, it may be possible to eliminate one cane and just walk with one assistive aid (or none at all).
The fact that your husband was still playing tennis suggests good health and good mobility. Both of these factors are in his favor in terms of recovery and rehab. If all goes well, he may very well be among the two per cent who regains his previous level of independence and function.